What is processor overclocking on the bus. Theory and practice of overclocking Intel Skylake processors on the BCLK bus

What is overclocking? This is a change in the normal operation of computer devices in order to increase their speed and increase the overall performance of the system. Apart from extreme overclocking, the goal of which is to squeeze the maximum out of a component and fix a record, overclocking makes it possible to meet the growing needs of applications and games without replacing equipment with more powerful ones.

Today I will show you how to overclock a processor (CPU). Let us consider the methods and means by which the performance and stability of an overclocked system are determined, as well as a simple way of returning it to the “overclocked” state.

Before you start

Any modern processors, even mobile ones, are capable of overclocking, although the latter, in the opinion of their creators, is contraindicated due to the impossibility of providing adequate cooling. Yes, an overclocked "stone" (now and further we will mean stationary PC processors) consumes more energy and emits more heat, so the first thing to take care of is a good cooling system. It can be of both air and liquid type, the main thing is that the magnitude of its heat removal ( TDP) corresponded to or exceeded the thermal power of the "stone". For small and inconsistent overclocking, the boxed cooler that came with the CPU is sufficient, but under increased load it will most likely annoy you with loud noise.

The second important detail is the power supply unit (PSU). If his strength is barely enough for the current power consumption of devices, he will not pull overclock. To calculate the required power of the PSU, taking into account overclocking, use: select from the lists the components that are installed on your PC, and click " Calculate».

Calculator version « Expert"Allows you to take into account the voltage and cycles of the CPU after overclocking, as well as the percentage of load on it (CPU Utilization). Choose the latter to the maximum - 100%.

Happy experiments!

Iron experiment: overclocking Intel Core i5-6400 and Core i3-6300T processors

Under pressure from Intel, overclocking Core CPUs has become the exclusive prerogative of wealthy users. Do you want more megahertz, lack performance? Buy the most expensive chip in the line, and with it a motherboard of the corresponding level! With the release of 14-nanometer Skylakes, it seemed that the "hut" turned towards us in front. Having crossed ourselves, we are examining a loophole for overclocking sixth generation Intel Core neo-overclocking chips.

One should not be surprised at this state of affairs. Starting with the second generation of Core processors (Sandy Bridge), the Core i5 and Core i7 series have two to three flagship processors equipped with an unlocked multiplier. These chips have a distinctive overclocking symbolism - the letter "K" in the name. Overclocking such models is reduced to a simple increase in the multiplier. The legendary Core i5-2500K, released in 2011, quietly overclocked to 5 GHz using an air cooling system. The rest of the models - those without the unlocked multiplier - were left without overclocking at all. Intel blocked overclocking on the bus.

With the release of the third generation Core, the situation has worsened. Instead of the solder used in Sandy Bridge, Intel has started adding mediocre thermal grease to the lid of the Ivy Bridge processors. As a result, a general decrease in overclocking potential and increased cooling requirements were added to the frankly short list of overclocking models with an unlocked multiplier. Enthusiasts remembered scalping again. Modern solutions - Haswell, Broadwell and Skylake - have adopted all anti-overclocker "chips". That's how we live.

Today, on the international day of overclocking, I will talk in detail about how to get around the ban on overclocking Skylake processors without an unlocked multiplier. And what is needed for this.

Chronology of events

In the summer of 2015, a line of modern 14-nanometer Skylake chips was released. This time Intel started with the top-end models, and therefore the overclocking Core i5-6600K and Core i7-6700K were the first to go on sale. The processors received not only an unlocked multiplier, but also the ability to overclock by increasing the frequency of the BCLK clock generator (bus overclocking). I was incredibly happy about this fact, since I had previously assigned this opportunity to all the other (not yet commercially available) Skylake “stones”. I was not happy for long: it soon became clear that only Core i5-6600K and Core i7-6700K were overclocked on the bus. And only on boards with Z170 Express logic.

In December 2015, Filipino enthusiast Dhenzjhen overclocked the Core i3-6320 processor to 4680 MHz. For this, the overclocker has increased the BCLK of the Supermicro C7H170-M motherboard to 120 MHz. A little later, another processor, Core i3-6100, was overclocked to 6104 MHz using liquid nitrogen, increasing the bus frequency to 165 MHz. It turned out that Supermicro engineers bypassed the lock. A little later, other manufacturers pulled up: ASRock, ASUS, BIOSTAR, EVGA, GIGABYTE and MSI. The listed companies have provided special firmware for a number of motherboards.

The first rule of the overclocking club: do not talk about the overclocking club . First, ASRock publicly announced the overclocking of non-overclocking Skylakes. A whole marketing technology has appeared called Sky OC: you update the BIOS, activate this function, overclock the processor via the bus. Paphos was immeasurable. Other manufacturers were more modest. For example, on the ASUS website you will not find the necessary firmware for the Z170 Express motherboard. BIOS'y transferred to overclockers from the hwbot.org forum. Thus, there is no way to dig into ASUS, all questions are for the enthusiasts. ASRock was eventually forced to drop Sky OC support. It is no longer in the new firmware. Information on other brands has not been reported at the time of this writing, but I do not exclude a scenario in which Intel will "squeeze" other brands as well. All this leads to certain thoughts. Firstly, motherboard manufacturers staged the "overclocking revolution". They are easy to understand: in 2015, sales of high-tech PCB fell by an average of 20%, and a return to the origins of overclocking is a good way to push the user to switch to a new platform. Second, Intel is principled. The chipmaker said: only Core i5-6600K with Core i7-6700K are overclocked - period. Bold.

Economic expediency

Overclocking makes life for the poor better. Initially, they began to overclock the iron solely for the sake of profit. The chain is simplified, but: we take a cheap processor, increase performance to the level of a more expensive representative, rejoice at the result and our own resourcefulness. Now, I repeat, Intel has turned overclocking into an additional bonus for those who do not initially save.

I won't go far for an example. Let's take a look at Intel's main competitor, AMD. The Reds have a line of FX processors. Each model is equipped with an unlocked multiplier. As a result, anyone can buy some FX-8320E (10,000 rubles) and, with a wave of the index finger of their right hand, turn it into an FX-8370 (17,000 rubles), or even even into an FX-9370 (19,000 rubles. ). And a decent portion of the hybrid APUs are equipped with an unlocked multiplier. In terms of loyalty to AMD enthusiasts, there are no complaints, their position is commendable.

However, with the "red" everything is clear. The ability to overclock all FX chips without exception is another trump card in the fight against Intel, which has long been setting the bar on the central processor market. I see no reason to reveal the ethical side of this issue. The article is not about that. It's just a fact: overclocking saves money. Another example is assembling the system unit directly on the LGA1151 platform. Let's say that the cheapest quad-core processor, Core i5-6400, will overclock to frequencies that obviously exceed the speed of the older model Core i5-6600. For this we need better cooling and a more expensive motherboard based on the Z170 Express chipset. Even so, we either save, or get more performance for the same money, or both at once. Sounds tempting, right? Unfortunately, overclocking non-overclocking Skylakes has several limiting factors. Let's talk about them further.

Overclocking methodology and pitfalls

I have already mentioned the first factor. Overclocking non-K Skylake chips requires a board exclusively based on the Z170 Express chipset. The limitation is formal, introduced either by Intel or by motherboard manufacturers. It is very easy to prove this, because the first successes in overclocking neo-overclocking chips were achieved with the Supermicro C7H170-M, built on the H170 Express logic.

A complete list of motherboards is easy to find on the Internet. I will list the most affordable models from ASRock, ASUS, GIGABYTE and MSI. I see no reason to buy more expensive motherboards for overclocking non-overclocking Skylake. The effect of saving so zealously promoted by me is lost. And assemblies in which motherboards are more expensive than processors look very strange.

A special BIOS version is required for overclocking via the bus. First, we reflash, then we do overclocking. Hyperlinks contain archives with BIOSes for all motherboards from leading manufacturers.

Motherboards that support overclocking Skylake processors without the unlocked multiplier
ASRock (download BIOS)	ASUS (download BIOS)	GIGABYTE (download BIOS)	MSI (download BIOS)
Z170 Pro4; Z170 Pro4S; Z170 Pro4D3; Z170 Gaming K4; Z170 Gaming K4D3.	Z170M-E D3; Z170-P D3; Z170M-Plus; Z170-P; Z170-K; Z170 Pro Gaming; Z170-E; Z170-A.	GA-Z170-HD3; GA-Z170XP-SLI; GA-Z170X-UD3; GA-Z170M-D3H; GA-Z170-D3H; GA-Z170-Gaming K3; GA-Z170-HD3P.	Z170A TOMAHAWK; Z170 KRAIT GAMING; Z170-A PRO; Z170A PC MATE; Z170A-G43 PLUS; Z170A SLI PLUS; Z170M MORTAR.

And here is my gentleman's set:

The only way to overclock the non-overclocker Skylake is to increase the BCLK clock (bus). The resulting frequency of the central processor depends on the product of the bus and the multiplication factor. Chips in one line are divided by speed. Some have a higher multiplier, some less. To overclock the Core i5-6400 to 4500 MHz, you will have to increase the bus frequency to 4500/27 = 167 MHz. In order for the Core i5-6600 to work at this speed, you need to raise the BCLK to 4500/33 = 136 MHz. In the second case, the probability of conquering the coveted 4.5 GHz is much higher.

Overclocking Skylake processors by BCLK frequency (bus)

BCLK Frequency \ CPU Multiplier
100 MHz
110 MHz
120 MHz
130 MHz
150 MHz
170 MHz

Overclocking is always a lottery. With non-overclocker chips, two factors affect the final result at once: the potential of both the chip itself and the motherboard. Since the release of the LGA1151 platform, the test lab has been familiar with several Z170 devices. Each board behaved differently. I managed to overclock ASUS MAXIMUS VIII EXTREME up to 360 MHz on the bus, and MSI Z170A GAMING M7 - up to 158 MHz.

The experiment was carried out on processors Core i5-6400 and Core i3-6300T (review). I was not looking for easy ways, since both models operate at very low multipliers. The most interesting thing is to overclock the quad core. According to statistics, this model overclocks very well, but, as we have already found out, a certain margin of safety is required from the motherboard as well. On the other hand, in comparison with the default 2.7 GHz overclocking, even up to 4 GHz will give a noticeable performance boost. What we need.

The third limiting factor is disabling the power-saving features of non-overclockers Skylake. For a successful overclocking, you need to deactivate the following functions: Intel SpeedStep, CPU C states and Turbo Boost (Turbo Mode). Below is a screenshot of the BIOS of the ASUS Z170-PRO Gaming motherboard. These three features are disabled in the Advanced / CPU Configuration / CPU Management Configuration branch. Without them, the CPU will always run at maximum frequency for a given voltage. Nothing wrong with that. Skylake is highly energy efficient and does not heat up as much as Haswell, for example.

The fourth limitation is that the temperature sensors of the processor cores are disabled. The thermal state of the crystal can be monitored only using the only available parameter CPU Package. This is the temperature of the area under the heat-distributing cover, the cores of the chip are heated to approximately the same value, but there are exceptions.

We met the flowers, it's time to talk about berries. Overclocking has two major limiting factors. The first one is: overclocking on the bus disables the integrated graphics core. Windows simply does not boot. If the system uses a discrete video card, then, frankly, the loss is small. In all other cases, you will have to forget about overclocking non-overclocking Skylakes.

The second major limiting factor is the slowdown in the execution speed of AVX / AVX2 instructions. Let's take the FPU benchmarks of the AIDA64 benchmark. Execution of Mandel and Julia patterns slowed down significantly on an overclocked processor. And in the VP8 test, the gain turned out to be somewhat frivolous. Therefore, the performance of software using AVX / AVX2 instructions may be degraded. What are these applications? The team's vector systems use video encoders, 3D modeling programs, some photo editors, and even computer games (GRID 2).

Having six limiting factors, especially those that affect overall system performance, is downright frustrating. All of them are software, implemented on purpose, because the same Core i5-6400 is no different from the overclocking Core i5-6600K. The conclusion suggests itself: sticks are put in the wheels of enthusiasts in order to reduce as much as possible the pool of those who want to raise their Skylake-chip several hundred megahertz, and, consequently, save on buying a more expensive and faster processor model.

Overclocking test samples

Armed with the knowledge gained, we proceed to the illegitimate overclocking of the Core i3-6300T and Core i5-6400. Disable Turbo Boost, SpeedStep and C states. Next, I set a multiplier for all processor cores corresponding to the nominal processor frequency. The Core i5-6400 has x27, the Core i3-6300T has x33. That's it, you can increase the speed of the clock generator. The stand used a classic set of DDR4-2133 RAM with CL15 delays. I didn't overclock it, so when raising the bus frequency, the effective RAM frequency was regulated by decreasing the divider (DRAM Frequency function in the BIOS of ASUS motherboards).

Core i3-6300T turned out to be quite mediocre in overclocking, which only confirms what was said earlier: overclocking is always a lottery! The frequency of the chip was increased from 3.3 GHz to 4.29 GHz. At almost 1 GHz, or 30%. "Mediocre" because everything is known in comparison. The Core i5-6400 frequency has increased from 2.70 GHz to, hold me seven, 4.94 GHz - almost 83%! The Internet is full of validations, when the junior 4-core Skylake was successfully overclocked to 4.7 / 4.8 GHz. So such a result is a pattern. To get 4.29 GHz for the Core i3-6300T, we had to raise the clock generator frequency to only 130 MHz, and the VCore voltage to 1.4 V. The absolute majority of motherboards based on the Z170 Express chipset can handle such overclocking. But overclocking the Core i5-6400 to 4.94 GHz will be a serious test, because you have to raise the bus to 183 MHz. The voltage is slightly higher - 1.42 V. Note that in both cases we are talking about stable frequencies, at such speeds the processors operate in 24/7 mode.

results

Test stand:

CPU:Intel Core i5-6600K, Core i5-6400, Core i3-6300T
Cpucooler: Corsair H110iGT
Motherboard: ASUSZ170PROGaming
Video card:AMDRadeonR9Nano, 4 GBHBM
RAM:DDR4-2133 (15-15-15-36), 2x 8 GB
Storage device:OCZ Vertex 3, 360 GB
Power Supply:CorsairHX850i, 850 W
Periphery: Samsung U28D590D , ROCCAT ARVO, ROCCAT SAVU
Operating system: Windows 10 x64

I'll start by examining the performance of the overclocked Core i5-6400 and Core i3-6300T in the AIDA64 cache and memory test. The main conclusion is that the built-in controller "did not suffer" during overclocking. The speed of operations with RAM has only increased with increasing processor frequency.

The overclocking paradigm is that the unlocked model, the Core i5-6600K, is overclocked to a more modest 4.7 GHz. Such is the potential of the K-processor that has fallen into my hands. Not surprisingly, in applications that do not use AVX / AVX2 commands, the overclocked Core i5-6400 is faster than the overclocked Core i5-6600K. And this is with a price difference of ~ 6,000 rubles.

The most obvious example is the CINEBENCH R15. In this benchmark, the overclocked Core i5-6400 outperformed the Core i5-6600K by 5%. If we compare the junior 4-core with itself before and after overclocking, the chip's performance increased by 47.5%. Core i3-6300T due to the increase of one gigahertz accelerated by 32.4%, respectively.

And here is the first bell. Overclocking made 3D graphics processing faster in Blender, but the gain was disproportionate to the increase in clock speed. The Core i5-6400 is 33.5% faster than itself, while the Core i3-6300T is only 12.5% faster. The overclocked Core i5-6600K wins: a 32% increase in frequency sped up rendering by 22%. But the Core i5-6400 in OC mode was 240 MHz faster.

And yet there is a sense of overclocking.

A noticeable decrease - just a decrease, not a decrease in the gain - in the performance of the non-overclocker Skylake is observed in LuxMark 2.0 and x265 Benchmark. In the first application, overclocking the Core i5-6400 by 83% resulted in a 15% decrease in scores. With the Core i3-6300T, the result is even worse: ray tracing slowed down by 40%.

The x265 Benchmark shows a similar, but not so sad picture. Core i3-6300T after overclocking slowed down by 12.5%, Core i5-6400, on the contrary, accelerated by 19.7%, but still lagged behind the overclocked Core i5-6600K by 24.6%.

It's important to remember that overclocking is always a lottery. I came across a very vigorous Core i5-6400, which eventually overclocked better than the specially developed Core i5-6600K. I cannot guarantee that other users will be able to at least repeat this result. In principle, the Core i5-6400 will overclock to 4-4.2 GHz for sure. This is also a very decent result. The main thing is that the motherboard is able to take 4200/27 = 155.5 MHz on the bus.

The Core i3-6300T is a bad "exhibit" for overclocking at home. All the salt of this chip comes in a very low TDP. Here and the potential for him is so-so. Better to overclock the obviously faster Core i3-6100 / 6300 models. Here it will certainly turn out to conquer the mark of 4.5-4.7 GHz.

I will put forward a hypothesis: AMD is not in a position to in any way infringe on the rights of enthusiasts in 2016. Consequently, a good part of Zen chips, if their frequency potential is at a height, will receive an unlocked multiplier. If hot competition flares up between manufacturers again, Intel will make concessions, including overclocking fans. Perhaps the golden era of overclocking, forgotten back in 2011, will return.

It so happened that for nearly twenty years of IT practice, I never had to deal with overclocking - somehow all other interests were. Nevertheless, choosing the configuration for the next new (although now far from new) computer, for some reason I settled on an Intel processor with an open multiplier - i5-2500K. Why I did this, I don’t remember now, perhaps I expected to figure out in my old age what this overclocking is. And then one evening, when there was nothing to do, I realized that the moment had come, and went deep into the study of the issue, and the next evening I applied what I had learned in practice. What I am going to report on.

Overclocking theory

Overclocking issues have been of interest to mankind all the time since the moment when computer technology came to the masses. The main driver of overclocking is the spirit of competition, passion, desire to achieve better results than others. Well, its main object is innocent processors, which are subjected to inhuman stress in order to obtain these very results.

There are two main ways to overclock a processor. The first is to increase the frequency of the BCLK clock generator, which, through multipliers, determines the frequency of the processor, memory, buses and bridges. This option is, in principle, universal, but it has many nuances and limitations associated with a specific processor and motherboard, so that your experiments do not lead to the death of the computer, you need to carefully understand everything. The second way is to change the processor multiplier, the same one by which BCLK is multiplied to get the operating frequency. This way is much safer (only the operating mode of the processor is changed, not the entire system) and simpler (essentially one parameter is responsible for overclocking), but there is one thing: the multiplier must be unlocked (allowed for change) by the processor manufacturer.

Initially, Intel processors had an open multiplier, but in the 90s of the last century, after a series of scandals related to re-labeling of processors by unscrupulous suppliers, when slow processors were overclocked and sold at the price of faster ones, the company blocked the multiplier. Since then, the unlocked multiplier was found only in top models "for enthusiasts", which, of course, were not cheap. The situation changed fundamentally with the advent of the second generation Intel Core processors (Sandy Bridge) - in their lineup there were models with an unlocked multiplier for the mass consumer, which received the K index.Initially, the cost of the K and non-K versions of one processor differed quite significantly, but now it has practically disappeared to no (for example, the difference between the Core i5 3570 and the Core i5 3570K today is 150 rubles).

So, Intel itself opened the way for "home", fast and highly skilled overclocking. It would be a sin not to take advantage of this opportunity, and I began my experiments. As a test stand, as I already said, my long-suffering home computer, by the way, was not prepared for overclocking, but rather, on the contrary, was chosen for reasons of economy and noiselessness.

Experiment

According to the specification, the i5-2500K operates at multipliers from 16 to 56. With standard settings and using SpeedStep, we have 16x idle and 34x under load. Now let's start the process.

Home overclocking has become so home overclocking that it can now be done directly from Windows without going into the BIOS. But we will still be oldfags for a start - only BIOS, only hardcore! However, there won't be much hardcore - we only need one parameter there; in the BIOS of my ASUS P8Z68-V LX motherboard, it is called CPU Ratio and is located in the CPU Power Management menu. To overclock the processor above the standard values, you will also need to enable the Turbo Mode option (it has nothing to do with Intel Turbo Boost, which, on the contrary, is recommended to be disabled).
The first overclock was tiny, up to 36x, to mark my entry into the overclocker ranks. However, there was no fanfare, and nothing happened at all, except for the frequency in the CPU monitor. The temperature also remained unchanged. The next level is 40x, a significant figure, until recently such a result (when accelerating “over the bus”) was considered a grandmaster. The height was taken without the slightest effort and without changing the voltage on the processor. But the temperature, unfortunately, crept up and at 100% load reached 68 degrees. There is nothing to be done, the cooling system installed on the computer proved to be completely unsuitable for overclocking.

Step three. 44x, or 1 GHz boost. After making the face a brick, I started the computer. “Well, no, that's enough,” he replied and flew into the blue screen. It is necessary to increase the processor voltage. I raised it immediately to 1.4 V to be enough. Now I decided to act through the GUI on Windows. In the AI Suite software supplied with the ASUS motherboard, the Turbo V EVO component is responsible for overclocking. For its work, this program uses the TPU (TurboV Processing Unit) controller on the motherboard. The TPU module is so intelligent that it can itself, without human intervention, overclock the system to the maximum possible parameters. Thus, the overclocking technology, from the point of view of the "teapot", has reached its highest point, when in order to obtain a result, it is enough to press one button "to make everything so that everything is hurt."
I could not really test the 4.4 GHz mode, because after a few seconds after starting the full load, the temperature rose to the maximum permissible, and I was forced to interrupt the experiment. However, I have no doubt that with normal cooling, the processor would be stable - numerous experiments by other users convince me of this. Speaking specifically about the i5-2500K, absolutely all processors work up to 4.5 GHz, the result of 5 GHz is quite common, and the most stubborn ones reached 5.2 GHz. Let me emphasize that we are talking about stable operation under a large (test or real) load. Thus, we are dealing with more than 50% increase in frequency with minimal material and mental costs.

Results and conclusions

As expected, the computational test results crawled up linearly with increasing frequency. As an example, I chose the CPU Queen integer "chess" test. As you can see, with maximum overclocking, our processor "pushed" not only the extreme i7 of the first generation, but also the server Xeon (although initially it was inferior to both).

Someone is probably wondering what happened to the Windows Performance Index? Almost nothing, it increased by only one tenth, from 7.5 to 7.6. However, do not forget that for Windows 7 the maximum index value is 7.9, so there could not have been a big jump.

Now let's try to answer the question, who needs this overclocking - except, directly, overclockers? However, it was answered before us: first of all - for fans of computer games. Experiments have shown that the processor power at standard frequencies is not enough to power top-end video cards, especially if there are several of them, and as the frequency rises to a certain limit, the performance in games also grows. Saturation occurs, by the way, at our "home" 4-4.5 GHz, it is at this frequency that the processor ceases to be the "bottleneck" of the entire system. In addition, the extra gigahertz will definitely be welcomed by people dealing with heavy media content, and, of course, dear fans of distributed computing. I would like to note that all categories of citizens will have to keep a close eye on the temperature of processors and their cooling system - otherwise, there will be a light "puff" and smoke will be guaranteed.

Last year's update of the processor microarchitecture represented by Intel Skylake did not bring any surprises in terms of productivity growth for desktop solutions, and we got the usual 5-10% superiority over the previous generation. But during the announcement of overclocking models, a very curious moment was noticed: and they received not only an unlocked multiplier, but also the ability to change the frequency of the base clock generator without losing stability. This fact gave enthusiasts hope for the revival of massive overclocking of processors, which were not initially aimed at the overclocking audience. But the miracle did not happen, and Intel blocked this possibility in conventional models. Fortunately, this limitation turned out to be only at the software level, and in mid-December the news feeds of technical resources filled with reports that the overclocking of Socket LGA1151 models without the “K” index. This fact has been repeatedly confirmed during our practical acquaintance with the new hardware platform, as you can see for yourself on the pages of our resource.

But at your request, we again decided to return to the very interesting topic of overclocking non-overclocking Intel Skylake processors, devoting a separate material to it. Let's try to summarize all the accumulated information and give practical recommendations for optimizing the system parameters. And the most important thing is to answer whether there is any practical value in all of this, which is especially important, given the not very favorable economic situation in the country. All experiments will be carried out on the example of the model. This processor is kindly provided by our partner - the online store PCshop.ua, where it is possible and buy for about $ 380.

A bit of history

What is overclocking or overclocking? This concept should be understood as a set of methods that allow computer components to operate at frequencies that are higher than the factory ones. The main goal of overclocking is to get the maximum performance out of the available hardware. Now this occupation can be called trivial. Any user can freely buy a suitable motherboard, a processor with an unlocked multiplier and overclock it in a couple of clicks. There is no sense of excitement and satisfaction from the work done. But this was not always the case.

At the dawn of its inception, overclocking was done exclusively by well-trained techies, using a soldering iron, jumpers and other hardware modifications. In short, the whole optimization process comes down to increasing the processor clock frequency, which is the product of two parameters - the multiplier and the base frequency. And since in most cases it is impossible to change the multiplier, you have to operate with the bus values. This became possible due to the fact that models of the same series differ only in frequency. That is, after manufacturing a batch of processors passes a series of tests, according to the worst results of which it is marked. So we get some models with a clock frequency, for example, 300 MHz, and others - 700 MHz. But not all copies are so unfortunate. For example, they can be deliberately slowed down due to the need to expand the range of the line, so if you have the necessary knowledge, this annoying injustice can be corrected. At the same time, we get the performance of the older model at a minimum cost. Isn't that wonderful?

In particular, one can recall 1998 and the popular Intel Celeron 300 and Intel Celeron 333 processors. At the recommended prices of $ 150 and $ 192, respectively, they outperformed Intel Pentium II 450 at $ 669 in overclocking. Yes, in this case, the risk of equipment failure increases, but this was in the past and happened through poor cooling, imperfect protection methods and the inability of the user himself to stop there in time. Now the progress has reached such a level that you are unlikely to be able to "burn" the processor.

The release of the first generation of Intel Core processors for Socket LGA775 in 2006 can be considered a truly golden era of overclocking. Overclocking itself has become much more convenient. To do this, it was enough to configure the necessary parameters in the motherboard BIOS or simply use special utilities for the OS. The younger models Intel Pentium E5xxx and Intel Core 2 Duo E7xxx became the favorites of enthusiasts, which in the right hands bypassed their more expensive brothers Intel Core 2 Duo E8xxx or even Intel Core 2 Quad. By the way, even now some Intel Core 2 Quad models and their server counterparts Intel Xeon work in users' system units. Thanks to the presence of four physical cores and good overclocking potential, they allow you to build an entry-level gaming system (by modern standards).

During this period, overclocking is becoming a truly massive phenomenon, and not just a way to save money. It even turns into a sports discipline thanks to the popular HWBOT resource. The essence of the competition is simple - to get the maximum result in benchmarks (3DMark, PCMark, Cinebench, Super PI, etc.) and fix it using the validation process. At the same time, top-end components and extreme cooling methods are used (phase transition systems, liquid nitrogen and dry ice). This state of affairs was facilitated by the hardware manufacturers themselves, who began to actively produce products specifically designed for overclocking. But this expanse did not last very long. Realizing that overclocking is becoming very popular, Intel decided to make money on it.

The last easily overclocked processors (via the bus) are models for Socket LGA1156 (Intel Nehalem microarchitecture), which were released back in 2009. Subsequent solutions lost this opportunity (starting with the Intel Sandy Bridge microarchitecture for Socket LGA1155), since the processor reference frequency (BCLK) became rigidly connected to all CPU nodes (processor cores, last-level cache memory, integrated graphics core, ring bus, controller memory, PCI Express and DMI buses). Therefore, even a slight change (above 104-107 MHz) led to unstable system operation.

For enthusiasts, the manufacturer has prepared two overclocking models: and. The processors received unlocked multipliers, through which the clock frequency is formed. But the price of these solutions has also increased in comparison with the conventional versions. That is, if you want to overclock - pay more. A pass to the world of overclocking has become available only for wealthy users and has lost its original meaning.

Yes, you can recall the available dual-core (Socket LGA1150, Intel Haswell microarchitecture) with an unlocked multiplier, but this is an isolated case.

However, with the release of the sixth generation Intel Core, the situation has changed, and now it is possible to overclock non-K-series processors, although it is actively discouraged by the CPU manufacturer. More on this in the next section of our article.

Overclocking Intel Skylake processors without the "K" index in theory

In Intel Skylake processors, engineers have separated the PCI Express bus and the chipset into a separate domain, the frequency of which remains fixed, regardless of BCLK changes.

The base frequency remained rigidly connected only with the internal nodes of the CPU: processor cores, last-level cache memory, integrated graphics core, ring bus and memory controller. Fortunately, the latter work well at higher frequencies. That is, in the new platform, you can overclock not only by manipulating the multiplier, but also by increasing the BCLK.

This was confirmed at the first acquaintance with overclocking models. But for some reason, Intel blocked overclocking in conventional processors, and even minor changes to the base bus were unsuccessful. The technology was named "BCLK Governor". But, as already mentioned above, the limitation is not of a hardware nature, and it is "treated" at the software level. To do this, it is enough to update the microcode of the motherboard.

The results were not long in coming. Overclocker "Dhenzjhen" overclocked Intel Core i3-6320 processor with a locked multiplier from 3.9 GHz nominal to 4.955 GHz... To do this, he used a SuperMicro C7H170-M motherboard with a special BIOS version. Soon, other manufacturers released updated BIOS versions, but only for motherboards based on the flagship chipset. The solutions were not, and remained deprived, although, apparently, there should not be any obstacles to this. Most likely, the manufacturers decided to spur sales of only more expensive models, which is a pity. It is noteworthy that only ASRock posted special versions of the microcode on its official website. The rest of the vendors - ASUS, BIOSTAR, GIGABYTE, EVGA and MSI - are distributing them through overclocking forums, fearing a negative reaction from Intel. As it turned out, there were reasons for this. And soon the company was reluctant to allow overclocking of conventional Intel Skylake processors. Despite this, you can still find the necessary BIOS versions on the network, which continue to appear with fixes and additions. So there is complete order.

But not everything is as simple as it seems at first glance. And when overclocking neo-overclocking processors over the bus, a number of nuances and limitations arise:

Energy-saving technologies stop working, and the processor always operates at the maximum frequency with the maximum supply voltage. Intel Turbo Boost Technology also becomes inactive.
Temperature monitoring of processor cores starts to produce incorrect data.
The graphics core integrated into the processor is disabled.
The execution speed of AVX / AVX2 instructions is reduced several times.

However, do not get upset prematurely. Experienced overclockers already recommend disabling all additional technologies: Intel Turbo Boost, Intel Enhanced SpeedStep and C-states, as any fluctuations in the multiplier and voltage can negatively affect the stability of the system during overclocking. Temperature monitoring can be performed using the CPU Package sensor, for example, using the HWiNFO utility. Disabling the embedded video will not upset anyone, since most overclockers have a discrete graphics card.

The only really unpleasant moment is the drop in the execution speed of AVX / AVX2 instructions. And this is very strange, considering that overclocking models are devoid of this drawback and perfectly overclock on the bus. And in fact, they are no different from the usual ones, except for an unlocked multiplier and a slightly higher frequency. We can assume that this is again a software limitation. AVX / AVX2 are mainly used in application programs such as video coding, 3D modeling and some graphics editors. Most everyday programs, including games, hardly use AVX instructions. The exceptions are GRID Autosport and DiRT Showdown, but as practice shows, there is nothing critical about that. Suffice it to recall the processor, which generally lacks support for vector instructions, but this does not prevent its owners from playing modern games.

Preparing for overclocking by BCLK

As you can already understand from the above, absolutely all processors of the Intel Skylake generation are suitable for bus overclocking: from Intel Celeron to Intel Core i7. But of the greatest practical interest are the younger models of each line, since at the minimum price, overclocking allows them to easily overtake and even bypass the more expensive older brothers in terms of performance. You can see for yourself in the reviews and . For clarity, we present a list of the most interesting overclocking models in the form of a pivot table:

Model name	Number of cores / threads	Base / dynamic frequency, MHz	Factor

But besides a suitable processor, you need a motherboard based on the Intel Z170 chipset. In our case, there will be three of them:, and ASUS Z170-P. Why is this done? Let's try to use their example to find out whether we can get a decent overclocking on affordable motherboards or if we still need specialized solutions. And we will not overclock the simplest processor - Intel Core i7-6700. If the boards cope with it, then with some Intel Core i3 and even more so. Before starting experiments, you need to find the necessary BIOS for your motherboard and flash it. To do this, we looked at HWBOT in the appropriate section of the forum.

Now you can go directly to the preparatory settings.

First, go to the UEFI BIOS and in the "Advanced \ CPU Configuration" section, set the "Boot Performance Mode" option to "Turbo Performance", and in the "CPU Power Management Configuration" subsection, turn off "Intel Turbo Boost", "Intel Enhanced SpeedStep" and C-states by choosing “Disabled”.
Next, go to the "Extreme Tweaker" or "Ai Tweaker" section (depending on the motherboard manufacturer, the names may be different) and switch the "Ai Overclock Tuner" option to the "Manual" mode. In this case, we will have full access to change all parameters at our own discretion.
Next, we fix the maximum multiplier of all processor cores in the "1-Core Ratio Limit" item.
So that the RAM does not become a limitation during overclocking, using the "DRAM Frequency" item we set its frequency to several points lower than the nominal, since when the bus changes, its frequency will also increase.

You can watch the video below for all the BIOS settings of motherboards:

BIOS setup ASUS MAXIMUS VIII RANGER for overclocking Intel Core i7-6700

BIOS setup ASUS Z170-P D3 for overclocking Intel Core i7-6700

BIOS setup ASUS Z170-P for overclocking Intel Core i7-6700

Now you can start directly overclocking the Intel Skylake non-K processor. The process itself is quite simple and boils down to increasing the bus frequency (BCLK Frequency) and gradually increasing the voltage supplied to the processor (CPU Core Voltage Override).

How to choose the right frequency? Recall that the processor frequency is calculated using the formula:

CPU Freq = CPU Ratio × CPU Cores Base Freq

Let's say we want our Intel Core i7-6700 with a multiplier of "x34" to run at 4400 MHz. To do this, we divide 4400/34 and get the BCLK equal to 129 MHz. The same rule applies for other processors. For convenience, we present the BCLK value to achieve typical frequencies of 4500 - 4700 MHz for the previously considered processors:

Model name	BCLK frequency, MHz	Factor	Clock frequency, MHz
Intel Pentium G4400
Intel Core i3-6100
Intel Core i3-6300
Intel Core i5-6400
Intel Core i7-6700

In this case, you need to monitor the temperature and check the stability of the system after overclocking.

Let's take a closer look at the allowable voltage and temperature values. Experienced overclockers consider the 1.4-1.45 V threshold safe for everyday use. attention to three more important parameters:

CPU VCCIO Voltage (VCCIO) - the voltage at the memory controller built into the processor. It is recommended not to exceed 1.10 V.
CPU System Agent Voltage (VCCSA) - voltage on the system agent and other controllers built into the processor. It is recommended not to exceed 1.20 V.
DRAM Voltage (Vdram) - supply voltage on RAM modules. Values up to 1.4 V can be considered conditionally safe.

For a more detailed acquaintance with the capabilities of each option, we suggest visiting ours.

Now about the temperature. If Intel specifies T CASE = 71 ° C, this means that the maximum allowable temperature in the integrated heat spreader (IHS) of the processor, which can only be measured by an external sensor, reaches 71 ° C. The mechanism for skipping clock cycles (throttling) turns on when it reaches 100 ° C according to the data of the internal sensors of the cores. Therefore, roughly speaking, the T CASE index at the level of 71 ° C can be considered equivalent to 100 ° C of the internal sensors of the nuclei.

Overclocking and testing

The following list of equipment was used for the experiments:

CPU	Intel Core i7-6700 (Socket LGA1151, 4.0 GHz, L3 8MB)
motherboards	ASUS MAXIMUS VIII RANGER (Intel Z170, Socket LGA1151, DDR4, ATX) ASUS Z170-P (Intel Z170, Socket LGA1151, DDR4, ATX) ASUS Z170-P D3 (Intel Z170, Socket LGA1151, DDR3, ATX)

RAM	2 x 8 GB DDR4-2400 HyperX Fury HX424C15FBK2 / 16 2 x 8 GB DDR3L-1600 HyperX Fury HX316LC10FBK2 / 16
Video card	ASUS GeForce GTX 980 Matrix Platinum (4GB GDDR5)
HDD	Seagate Enterprise Capacity 3.5 HDD v4 (ST6000NM0024) 6TB SATA 6Gb / s
Power Supply	Seasonic X-560 Gold (SS-560KM Active PFC)
	Philips Brilliance 240P4QPYNS
Video capture device	AVerMedia Live Gamer Portable
Operating system	Microsoft Windows 8.1 64-bit

The Intel Core i7-6700 test processor has a "batch code" L542B978 - 96000, which contains information about the place, date and production batch. In our case, it was produced in the 42nd week of 2015 (between October 12 and 18) in Malaysia with a batch number of 96000.

Overclocking was carried out on motherboards ASUS MAXIMUS VIII RANGER, ASUS Z170-P D3 andASUS Z170-P in three modes:

Without raising the tension.
Intermediate overclocking with a slight rise in voltage for stable operation at 4400 MHz.
Maximum stable overclocking.

The voltage of 1.095 volts in the BIOS (according to monitoring data, 1.104 V) is taken as nominal, since the boards independently set it at maximum load in a fully automatic mode. We checked the stability by passing the benchmark and a 15-minute stress test in RealBench 2.41. This time is quite enough to determine stability. In this case, the heating was one of the highest, which is unlikely to be achieved under real conditions of use. By the way, classical stress tests like Linpack or Prime95 are not suitable for this role, since they actively use AVX instructions, which slow down when overclocking non-overclocked processors and cannot recreate the maximum load. The monitoring was carried out by the utilities HWiNFO and CPU-Z.

The first to go into battle was the ASUS MAXIMUS VIII RANGER gaming board with excellent overclocking capabilities. At voltage 1 , 104 V and manually raising the reference frequency to 121 MHz, the speed of the Intel Core i7-6700 was brought up to 4113.86 MHz, which is an increase of 21% relative to the nominal.

At the same time, the power consumption of the system increased insignificantly: from 51 W in idle mode (all energy-saving technologies are activated) and 223 W under stress load to 61 W and 230 W, respectively. The maximum temperature under stress did not rise above 51˚C.

On ASUS Z170-P D3, it turned out to achieve 4107.23 MHz with the same 1 , 104 V and a BCLK value of 121 MHz.

Power consumption has increased from 48W and 223W to 62W and 230W, respectively. The maximum temperature did not rise above 53˚C.

ASUS Z170-P obeyed a slightly lower processor frequency, namely 4060.70 MHz at voltage 1 , 104 V and a BCLK value of 119.5 MHz.

In this operating mode, power consumption has increased from 48 W and 225 W to 59 W and 230 W, respectively. The temperature did not rise above 52˚C.

To accelerate Intel Core i7-6700 to 4400 MHz on ASUS MAXIMUS VIII RANGER, it was necessary to raise the base frequency to 129.5 MHz, and the voltage to 1.215 V, although, judging by the readings of the utilities, at times it reached 1.232 V. The frequency increase was 29 , 4% of the nominal.

The power consumption figures were 64W idle and 240W under load - still fairly modest values. The temperature is kept in the range of 60-64 ˚C.

For stable operation of the Intel Core i7-6700 at 4400 MHz on the ASUS Z170-P D3, it was necessary to set a slightly higher voltage - 1.230 V (according to monitoring data - up to 1.248 V).

Power consumption was at 63 W and 249 W, respectively, and temperatures were at 70˚C.

On ASUS Z170-P for 4400 MHz, it was required to raise the voltage to 1.215 V (according to monitoring data - up to 1.232 V).

At the same time, power consumption was 63 W and 265 W in idle and load, respectively. The maximum temperature did not rise above 63˚C.

Let's move on to the most interesting part - maximum overclocking.

On ASUS MAXIMUS VIII RANGER, it turned out to achieve a frequency of 4708.22 MHz with an increase in BCLK to 138.5 MHz. As a result, we got a 38% increase to the nominal frequency. At the same time, the voltage was increased to 1.415 V (1.472 V according to monitoring data), and to compensate for its drawdowns in the BIOS settings, the Load Line Calibration (LLC) parameter was set to the LEVEL -6 position.

At the same time, the power consumption of the processor increased to 74 W and 322 W in idle and load, respectively, while the processor itself warmed up under stress load up to 98˚C.

The maximum stable frequency on the ASUS Z170-P D3 was 4523 MHz when the reference frequency was raised to 133 MHz. The increase was 33% against the nominal value. To do this, we had to raise the supply voltage to 1.415 V (1.408 V according to the monitoring data) and set the value for “LLC” to “LEVEL -5”.

In this mode, power consumption has increased to 71 W and 310 W, respectively. Under stress, the temperature did not exceed 85˚C.

On the ASUS Z170-P, we made the processor run stably at 4691 MHz with a BCLK of 138 MHz. In this case, it was necessary to raise the voltage to 1.415 V, and set "LLC" to "LEVEL -6".

In this mode, power consumption was 73 W and 325 W, respectively, and the temperature at peak load reached 96˚C.

For a visual assessment of the overclocking results obtained, we suggest taking a look at the summary table:

	ASUS MAXIMUS VIII RANGER
	Overclocking Intel Core i7-6700
Processor frequency, MHz
BCLK frequency, MHz
CPU voltage, V
Power consumption of the entire system idle / load, W
Maximum temperature, ˚C

Analyzing the results of overclocking Intel Core i7-6700, we can safely say that all tested motherboards coped with the task. True, some are better, and some are a little worse. If you want uncompromising overclocking, then a solution of the level of ASUS MAXIMUS VIII RANGER may well give it. In this case, all thanks to the enhanced 10-phase digital power subsystem, which perfectly copes with its direct duties at any type of load and at the highest voltages, without a hint of drawdowns. The board clearly has a large margin of safety for extreme overclocking. However, it is quite possible for economical users to recommend solutions like ASUS Z170-P or ASUS Z170-P D3. For example, these boards also have a 7-phase digital power system, good cooling and wide customization options. That is, they have everything you need to get a decent overclocking. The main thing is to take care of a good cooling system. But you should also understand that overclocking is a lottery. It is not a fact that your processor will be able to repeat the achieved performance. Fortunately, all Intel Skylake models that have visited our laboratory have conquered the 4.6 GHz mark. So, on the other hand, you may be luckier than ours.

In conclusion, we propose to take a look at the results of RealBench v.2.41 at the maximum frequency of Intel Core i7-6700

The places were distributed according to the obtained maximum processor frequency: ASUS MAXIMUS VIII RANGER, ASUS Z170-P and ASUS Z170-P D3. On average, the increase in productivity was about 24% relative to the nominal.

Energy consumption

Overclocking Intel Core i7-6700 pleased us pleasantly, but let's estimate how much its power consumption has grown after such optimizations. To do this, we will use the results obtained on the ASUS MAXIMUS VIII RANGER motherboard.

Looking at the graph, you can see that while the voltage on the processor remains unchanged, the increase in power consumption is linear with increasing frequency. But as soon as we significantly increase the voltage on the processor, a sharp jump in consumption is observed. As a result, the power consumption of the Intel Core i7-6700 at maximum overclocking increased by 100 W in comparison with the nominal. This is the price to pay for increased productivity. This should be taken into account when conducting experiments and take care of a high-quality power supply.

Analysis of the practical benefits of overclocking

Let's say you want to build a mid-range computer. What is the best choice? The processor is simpler and the components for overclocking or the processor is more powerful, and the components are cheaper. Let's try to figure it out.

CPU	Intel Core i3-6100 tray - $ 127 (3175 UAH)	Intel Core i5-6400 BOX - $ 199 (4986 UAH)
Motherboard
	DeepcoolGAMMAXX 300 - $ 23 (584 UAH)
Power Supply
total amount	$ 349 (8712 UAH)	$ 345 (8612 UAH)

As you can see, the assemblies turned out to be almost the same in price. But thanks to overclocking to 4.5 - 4.7 GHz, the Intel Core i3-6100 bypasses the Intel Core i5-6400 by 3-5%, depending on the type of load. In fairness, it should be noted that 3-5% includes not only game applications, but also specialized ones (rendering, mathematical calculations, coding, and so on). But if you take a computer exclusively for games, then an overclocked Intel Core i3-6100 can produce FPS, comparable to the configuration on an Intel Core i5-6600 operating at par. In addition, no one bothers you to save money on the power supply and the motherboard. In the first case, it all depends on the appetite of your video card, and in the second - on the required functionality and loyalty to a particular manufacturer. In this case, the profit can be much more significant.

What is the situation in the higher price range? Let's take a look at such an assembly.

CPU	Intel Core i5-6400 tray - $ 192 (4785 UAH)	Intel Core i5-6600 BOX - $ 239 (5969 UAH)
Motherboard	ASUS Z170-P - $ 141 (3518 UAH)	MSI B150M MORTAR - $ 96 (2400 UAH)
	ZALMAN CNPS10X Performa - $ 34 (855 UAH)
Power Supply	Aerocool KCAS-600 - $ 58 (1455 UAH)	Aerocool KCAS-500 - $ 50 (1257 UAH)
total amount	$ 425 (10609 UAH)	$ 385 (9610 UAH)

As a result, we get 10% more expensive and 5% slower to build on Intel Core i5-6400 compared to Intel Core i5-6600. But if you overclock the Intel Core i5-6400, then it already bypasses the older brother by 10-15% and even comes close to the much more expensive Intel Core i7-6700 ($ 369 or 9207 UAH). This can be seen on the example of testing. In this case, overclocking is fully justified, especially if you initially looked to the side. The difference in price between them is $ 71 (UAH 1772). And the money saved can be reported to a more efficient video card or directed to other needs.

Let's say a few words about the Intel Core i7-6700. The difference between it and the Intel Core i7-6700K is about $ 31 (778 UAH), but both of them are excellent overclocking. It is unlikely that you will be able to achieve much savings, but as always, the choice is yours.

conclusions

Summing up the material, we have two news for you: good and bad. Let's start with the bad one. If you work with specialized programs like video encoding, 3D modeling and the like that use AVX / AVX2 instructions, then overclocking non-overclocking Intel Skylake processors is contraindicated for you. This is because in this case, the speed of execution of these very instructions decreases and, as a result, a drop in overall performance is observed. If you still need to get more performance, and you plan to overclock the processor, then the choice remains only between Intel Corei5 - 6600K and Intel Core i7-6700K.

Now for the good news. In all other cases, overclocking is not only possible, but also necessary - especially in game assemblies. The same Intel Core i3-6100 when overclocked can produce comparable performance with full-fledged 4-core processors working at par. And the younger Intel Core i5-6400 not only bypasses the older brothers in the line, but can even come close to the Intel Core i7-6700. At the same time, for a decent overclocking (most Intel Skylake processors easily take the 4.5-4.6 GHz line), it is not necessary to buy an expensive top-end motherboard, but you can get by with affordable models. The main thing is to take care of good cooling and a high-quality power supply.