Overclocking Kaby Lake
While many will argue that Intel is utilizing some of the overclocking headroom that Kaby Lake provides to increase stock clocks and offer some semblance of performance increases over Skylake, the truth is that the updated 14nm+ process technology allows Intel to do more with the same architecture and design.
With base clock-aware frequency and voltage curves, and a new AVX offset ratio to lower AVX clock speed to avoid the thermal constraints those instructions can create, Intel thinks that the overclocking capability of Kaby Lake should be higher than older architectures. The truth is somewhere in the middle; the overclockability relative to stock speeds looks about the same as Skylake, but with higher starting values – and that still means going above 5.0 GHz with modest cooling.
For me, a pretty basic overclocker that I think represents the vast majority of the consumer market, the process of overclocking Intel CPUs over the last several generational steps has been unchanged when working on unlocked parts:
- Adjust the multiplier to a fixed number on all cores until instability occurs
- Increase voltage until given clock speed is stable
- Adjust multiplier again until higher voltages adversely affect temperature or have no affect
On the ASUS Maximus IX Code motherboard this was dead easy and I quickly found that the limit on my review sample was 5.1 GHz at a fixed voltage of 1.375v.
The screenshot above shows our Core i7-7700K running on all cores at 5.1 GHz at 1.375v during a run of POV-Ray, after completing a solid hour of stability testing. That is 600 MHz faster than the stock Turbo clock rate and a good 300-400 MHz faster than I have been able to reliably run at on my various Core i7-6700K parts over the last year. Temperatures on the CPU (based on readings from the ASUS AI Suite III software) never exceeded 70C while using a Corsair H100i GTX AIO cooler.
What does that net us in terms of usable performance over stock?
- Stock: 2080.87
- 5.1 GHz: 2368.04
- Diff: +13.8%
- CineBench 11.5
- Stock: 10.66
- 5.1 GHz: 12.10
- Diff: +13.5%
- Stock: 296.61
- 5.1 GHz: 345.46
- Diff: +16.4%
Overclocking might be considered a dying art by many, but gaining an additional 13-16% in performance for highly threaded applications with very little effort (and maybe a bit of extra cost for a better cooler) is hard to argue with. Morry will be following up with a more detailed look at overclocking with a higher end water cooling setup next week.
And there's just something about being able to run above that 5.0 GHz mark that makes me smile.