Skylake Z170 overclocking experience: 24/7 air, water and sub-zero cooling OC results


Posted on August 28 2015



Looking to overclock your new Skylake CPU?

We compared air, water and sub-zero cooling to find the perfect 24/7 OC setting.

Overclocking Skylake: The basics

With Intel moving the FIVR (Fully Integrated Voltage Regulator) out of the CPU, leaving it to motherboard manufacturer's to include it in their PWM design, overclocking the new i7-6700K & i5-6600K processor on the Z170 platform should be a dream. But is it? The choice of motherboard is more important than ever and we chose wisely, so let's find out ;)

Z170 allows for extreme base clock flexibility, but for 24/7 OC we are focusing on the simplest overclock. So simply up the core voltage to a reasonable amount, of course staying within your setups' thermal limits (recommend not to go over 87°C / 1.48v under full load) and changing the multiplier until confronted with a blue screen or other unstable scenarios. Sounds very familiar to overclocking Sandy Bridge doesn't it? Let's see if the results are also similar or even better..

In our hunt for the best 24/7 overclock we used:

- Motherboard: MSI Z170A GAMING M7
- CPU: Intel® Core i7-6700K
- Memory: Corsair Vengeance LPX 8GB Dual Channel DDR4 @ 2800MHz C15
- SSD: Crucial MX200 120GB M.2
- PSU: Cooler Master Silent Pro Gold 1200w 
- OS: Windows 10 Professional 64-bit build 10024

Cooling solutions:
- Air cooling: Cooler Master Hyper TX3 EVO
- Water cooling: Corsair Hydro Series H100i
- Sub-zero cooling: LittleDevil Phase Change PC-V2

Stability testing:
- Intel® XTU
- Cinebench R11.5  v.11.529



Z170 24/7 OC results: Air cooling

Starting off the air cooling challenge, the Cooler Master Hyper TX3 EVO, much used as an upgrade over the Intel stock cooler, was chosen. To keep things safe, a maximum load voltage of 1.35v is used to test the CPU temperature and it became apparent it already hit the max. since the temperature quickly raised to a hot 83°C.

So, pusing the vCore @ 1.35v has proven to be the sweet spot on air cooling in terms of temperature. Let's find out if this is also the case in the quest to find the maximum stable multiplier. As most overclockers would expect, starting at 4500MHz should be a walk in the park for the 6700K, and it definately was.
Experiencing some slightly unstable scenarios at 4800MHz, we finally settled for a nice 4700MHz clock speed.
Our CPU scored a nice 1355 Marks in Intel XTU and 11.22 pts in Cinbench (without OS/benchmark optimizations). Not a bad start, especially considering the fact a common air cooler is used.

XTU_4.7ghz_1355 - Copy

CB11.5_4.7ghz_11.22 - Copy

Z170 24/7 OC results: Water cooling


The first results make us crave for more. The Corsair Hydro Series H100i closed loop water cooling solution is one of the most used pre-built water coolers out there. Let's see if we can use it to squeeze even more from our 6700K. This time we up the vCore to 1.44v load to give it enough for a speed increase since CPU core clock scaling becomes poor at a certain speed/voltage point.
We reached 81°C when testing, so we kept it at 1.44v.

Pretty sure we could reach a stable 4800MHz we immediately skipped to 4900MHz. This proved to be stable and we tried to reach the magic 5.0GHz, but it failed to successfully complete 3 runs of XTU and Cinebench. At 4.91GHz we reached 1383 Marks in Intel XTU and 11.80 pts in Cinbench (without OS/benchmark optimizations).

So we already had a little taste of 5.0GHz on Skylake, let's see where we end up freezing it.

XTU_4.9ghz_1383 - Copy

CB11.5_4.9ghz_11.80 - Copy

Z170 24/7 OC results: Sub-zero cooling



Sky's the limit with our LittleDevil LD PC-V2 Phase Change cooling. After securely insulating the motherboard with eraser and cleaning cloth around the socket to prevent possible condensation damage, we can fire up (uhm...yeah...) the Phase Change unit.
These units are sometimes used for 24/7 PC cooling and are also available pre-fitted in a case. 
Since generally vCore isn't going to be an issue when going sub-zero you still need to keep away from the 'crazy-zone' to prevent imminent damage to the CPU (below 1.7v).

Since we are looking for 24/7 overclocking settings and the 6700K CPU is based on 14nm, a maximum load voltage of 1.5v is used. When moving from 1.35v to 1.44v load already showed scaling was getting worse, an increase of 6mV wasn't expected to do a lot for the 6700K, but boy were we wrong..With the Phase Change idling at -45.5°C it was time to see what the 6700K had left.

Immediatly moving to 5.1GHz proved stable. Good, time for more! Shooting for the stars, 5.4GHz failed almost instantly. Surprisingly, 5.3GHz was rock solid stable and managed to set a score of 1411 Marks in Intel XTU and 12.85 pts in Cinbench (without OS/benchmark optimizations). Something in XTU prevented the score to go above 1411 as the same score was reached at 'only' 5.1GHz, Cinebench however showed a nice increase moving to 5.3GHz.

 XTU_5.3ghz_1411 - Copy

CB11.5_5.3ghz_12.85 - Copy

So there you have it, 24/7 overclocking on the new Z170 platform using air, water and sub-zero cooling.
Looking at the results we can conclude that overclocking has definately improved over Haswell and it is expected to see a lot of 24/7 5.0GHz results on (custom) water cooling. Since sub-zero is more expensive and exotic, a decent water cooling solution is recommended to enjoy great Skylake overclocking daily.

CPU Speed (OC)

Cooling Type

Load Core Voltage

Max. Temperature

4.5GHz - 4.7GHz (12% OC)

Air cooling



4.7GHz - 4.9GHz (17% OC)

Water cooling



4.9GHz - 5.3GHz (26% OC)

Sub-zero cooling



Now show us what you got!

Want to go even more extreme and do LN2 overclocking? Here is a professional guide to help you:




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