Auto & Manual Overclocking Results
Auto & Manual Overclocking Results
Though it might feature a new socket, this LGA2066 platform is still fundamentally identical to the LGA2011 series that came before it when it comes to overclocking. Much like Broadwell-E, the new Skylake-X processors are still based on a 14nm process, so you can definitely still theoretically use up to 1.35V CPU core voltage pretty safely. However, that only applies to the i7-7800X and i7-7820X. When it comes to the i9-7900X you can't use that much voltage given the incredible amount of heat it outputs when overclocked and overvolted. Personally, even with an absolutely top-notch dual-fan air cooler or high-end dual-fan AIO we wouldn't recommend more than 1.25V, and even that much voltage will be problematic for most cooling solution. In order to avoid creating extra heat, we also recommend being conservative with the other system voltages, namely the cache/mesh voltage, the system agent voltage (VCCSA) and the I/O voltage (VCCIO). Ideally, you shouldn't need to apply more than 1.15V to the cache/mesh while still being able to reach a ~3200MHz frequency, while near default VCCSA and VCCIO values of 0.95V and 1.05V should allow you to reach memory speeds of up to DDR4-3733.
The rules for Kaby Lake-X are unsurprisingly similar to mainstream Kaby Lake. Our personal pointers are to increase the vCore up to around 1.35V if you're cooling can handle it, while increasing the VCCIO up to 1.20V, and the System Agent voltage up to 1.25V if you plan on increasing the cache or memory frequency. If you are trying to achieve the highest possible DDR4 memory speeds, increasing the VCCIO to 1.30V and vSA to 1.35V might be worth trying out. These last two are really only needed if you plan on seriously pushing the uncore/cache frequency or the memory frequency.
All of the LGA2066 processors are multiplier and BCLK unlocked, but unless you're trying to extract every last megahertz there's no reason to go crazy increasing the BCLK above 103-105Mhz since you can achieve similar results by just tweaking the various multipliers instead.
Lastly, we highly recommend that you avoid stress testing Skylake-X with the latest build of Prime 95. The simple fact of the matter is that due to its use of AVX its puts an entirely unrealistic load on the CPU, which causes both CPU and VRM temperatures to skyrocket until one or the other will start throttling. If you aim for Prime 95 stability/temperatures you will be robbing yourself of hundreds of megahertz of overclocking potential.
The X299 Taichi motherboard supports three types of automatic overclocking, one software-based and two found within the UEFI. Within the multi-purpose ASRock F-Stream software suite there is the EZ OC feature, which is a semi-intelligent approach to automatic overclocking. It can accessed by selecting the Performance Mode option and then clicking on the Advanced sub-menu. There aren't really any available options, you just need to click on the Start button and the utility starts off the overclocking process at default clocks and slowly increases to the the frequency until a reasonable sweet spot is found.
Within the UEFI BIOS, there are two different modes - EZ Mode and Advanced Mode - both of which offer distinct automatic overclocking features. In the EZ Mode, there is a CPU EZ OC button that once you click and save will automatically apply an overclock preset. In the Advanced Mode, there is the Optimized CPU OC setting, with four available options, ranging from Turbo 4.2GHz to Turbo 4.8GHz. This is another feature that relies on presets, so it can't customize the overclock to best suit your particular system. On the plus side, it is as quick and easy as selecting the desired option and exiting the UEFI.
With all of that said, let's start off with the software-based EZ OC feature:
As mentioned above, in the EZ OC section of the F-Stream app there is option to select presets of up to 4.8GHz when a Core i9-7900X is installed. As always, we tried that most aggressive preset and while we were able to boot into Windows and even pass a 16-thread HyperPI stress test it would consistently crash during the Cinebench multi-threaded test. This preset set a high 1.319Vcore which is more than sufficient to theoretically stabilize our i-7900X at 4.8Ghz, the temperatures were absolutely very problematic with that much voltage. As a result, we ended up choosing the second most aggressive preset - Turbo 4.6Ghz - which proved to be perfectly stable throughout our tests, at least in part due to its more reasonable 1.26Vcore. The memory speed was not touched, nor was the cache frequency, so those voltages were not touched.
When we swapped in a Core i7-7740X, the presets went up to 5.0GHz and our chip has absolutely no issues hitting that, especially with 1.312V. Once again, neither the memory cache or cache frequency were overclocked.
Next up we will take a look at one of the two UEFI-based automatic overclocking options:
The first of two types of automatic overclocking found in the UEFI is the CPU EZ OC button. Since it's found in the EZ Mode part of the UEFI, this feature is super simple; you just click on the icon, save & exit, the system reboots and the overclock is applied. In the case of the i9-7900X, lightly threaded workloads pushed the frequency up to a max of 4.3GHz at 1.17Vcore, while heavily multi-threaded workloads saw the cores running at 4.0GHz at 1.08Vcore. When we installed the i7-7740X and enabled the CPU EZ OC feature all the cores just ran at 4.6GHz at 1.260-1.264V no matter the type of workload. Overall, this feature might be super-duper simple and worthwhile for novice users or those will mediocre cooling, but the software-based EZ OC feature is distinctly superior if you're more interested in gaining some additional performance.
In the Advanced Mode section of the UEFI, there is the Optimized CPU OC setting with four available presets options that vary depending on which processor you have installed. Fundamentally speaking this is exactly the same feature as the aforementioned software-based EZ OC feature. Once again, we were not able to run our i9-7900X at 4.8Ghz due to instability and temperature issues, however the less aggressive 4.6Ghz worked without issues. Likewise, we were once again able to apply the Turbo 5.0GHz to our Core i7-7740X.
As you can see, we were able to push the Core i9-7900X to 4.7GHz with our self-imposed 1.25Vcore limit. With an eye towards further managing temperatures, we also set a -1 AVX offset and a -2 AVX-512 offset, which limits the cores to 4.6GHz and 4.5GHz when those particular extensions are used. When it came time to overclock the cache/mesh and memory, we simply set the cache voltage to 1.15V, system agent voltage to 0.95V and the I/O voltage to 1.02V. This allowed us to increase the cache/mesh frequency from 2400MHz to 3200MHz - which provides a VERY nice performance boost - and we overclocked the memory from DDR4-3200 14-14-14 to DDR4-3733 16-16-16. We could have likely pushed the memory much higher, but since we are already tickling the 100GB/s memory read bandwidth mark, more is not really necessary.
Our dainty little Core i7-7740X proved its high frequency capabilities by hitting 5.2GHz with a relatively conservative 1.35V. The temperatures were still very manageable - somewhere in the low 70°C range - so 5.3 or 5.4GHz is certainly not outside the range of possibility for those willing to give it some additional voltage. The uncore/cache hit a wall at modest 4400MHz with 1.35VCCSA and 1.300VCCIO, but on the plus side we were able to push our memory kit all the way up to DDR4-4000, albeit with fairly loose timings.
Overall, overclocking on this motherboard was a problem-free experience. Even despite the monstrous power demands of our overclocked Core i9-7900X we never felt the need to baby the motherboard or give it any active cooling. We are now a full three months after launch day, so there's been ample UEFI updates and all the kinks appear to have been ironed out (Prime95 VRM load aside). Obviously, the automatic overclocking results speak for themselves, they are as high as you could possibly want on either of these processors...and even perhaps higher than you can reasonably cool in the case of the Skylake-X chip.
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