At the time of our Skylake review of both the i7-6700K and the i5-6600K, due to the infancy of the platform and other constraints, we were unable to probe the performance uptake of the processors as they were overclocked. Our overclock testing showed that 4.6 GHz was a reasonable marker for our processors; however fast forward two weeks and that all seems to change as updates are released. With a new motherboard and the same liquid cooler, the same processor that performed 4.6 GHz gave 4.8 GHz with relative ease. In this mini-test, we tested our short-form CPU workload as well as integrated and discrete graphics at several frequencies to see where the real gains are.

In the Skylake review we stated that 4.6 GHz still represents a good target for overclockers to aim for, with 4.8 GHz being indicative of a better sample. Both ASUS and MSI have also stated similar prospects in their press guides that accompany our samples, although as with any launch there is some prospect that goes along with the evolution of understanding the platform over time.

In this mini-test (performed initially in haste pre-IDF, then extra testing after analysing the IGP data), I called on a pair of motherboards - ASUS's Z170-A and ASRock's Z170 Extreme7+ - to provide a four point scale in our benchmarks. Starting with the 4.2 GHz frequency of the i7-6700K processor, we tested this alongside every 200 MHz jump up to 4.8 GHz in both our shortened CPU testing suite as well as iGPU and GTX 980 gaming. Enough of the babble – time for fewer words and more results!


We actually got the CPU to 4.9 GHz, as shown on the right, but it was pretty unstable for even basic tasks.
(Voltage is read incorrectly on the right.)

OK, a few more words before results – all of these numbers can be found in our overclocking database Bench alongside the stock results and can be compared to other processors.

Test Setup

Test Setup
Processor Intel Core i7-6700K (ES, Retail Stepping), 91W, $350
4 Cores, 8 Threads, 4.0 GHz (4.2 GHz Turbo)
Motherboards ASUS Z170-A
ASRock Z170 Extreme7+
Cooling Cooler Master Nepton 140XL
Power Supply OCZ 1250W Gold ZX Series
Corsair AX1200i Platinum PSU
Memory Corsair DDR4-2133 C15 2x8 GB 1.2V or
G.Skill Ripjaws 4 DDR4-2133 C15 2x8 GB 1.2V
Memory Settings JEDEC @ 2133
Video Cards ASUS GTX 980 Strix 4GB
ASUS R7 240 2GB
Hard Drive Crucial MX200 1TB
Optical Drive LG GH22NS50
Case Open Test Bed
Operating System Windows 7 64-bit SP1

The dynamics of CPU Turbo modes, both Intel and AMD, can cause concern during environments with a variable threaded workload. There is also an added issue of the motherboard remaining consistent, depending on how the motherboard manufacturer wants to add in their own boosting technologies over the ones that Intel would prefer they used. In order to remain consistent, we implement an OS-level unique high performance mode on all the CPUs we test which should override any motherboard manufacturer performance mode.

Many thanks to...

We must thank the following companies for kindly providing hardware for our test bed:

Thank you to AMD for providing us with the R9 290X 4GB GPUs.
Thank you to ASUS for providing us with GTX 980 Strix GPUs and the R7 240 DDR3 GPU.
Thank you to ASRock and ASUS for providing us with some IO testing kit.
Thank you to Cooler Master for providing us with Nepton 140XL CLCs.
Thank you to Corsair for providing us with an AX1200i PSU.
Thank you to Crucial for providing us with MX200 SSDs.
Thank you to G.Skill and Corsair for providing us with memory.
Thank you to MSI for providing us with the GTX 770 Lightning GPUs.
Thank you to OCZ for providing us with PSUs.
Thank you to Rosewill for providing us with PSUs and RK-9100 keyboards.

Frequency Scaling and the Handbrake Problem
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  • hyno111 - Saturday, August 29, 2015 - link

    Is there a temperature chart for overclocking? Reply
  • sonny73n - Sunday, August 30, 2015 - link

    Ian seems to miss the most important part in OCing. Reply
  • MrSpadge - Thursday, September 3, 2015 - link

    The temperature depends strongly on your cooling, TIM application etc. If Ian included those numbers, people would be shouting "but I get different values with..." Reply
  • kneelbeforezod - Saturday, August 29, 2015 - link

    12% better performance for a 32% power increase. uha. Reply
  • StrangerGuy - Saturday, August 29, 2015 - link

    I OCed a cheapo AXP1700 by 25% on a budget nForce 2 board and stock cooling simply with FSB 266->333. I OCed my $183 E6300 that surpassed a $1000 X6800 in performance.

    Now, Intel and Asus et al thinks they are doing us a favor top-end mainstream CPUs that are barely overclockable on even on the most pricey of mobos, and hardly anyone calling out their bullshit, just because of unlocked multipiers? Gimme a break.

    Am I the only sane guy here or what?
    Reply
  • jihe - Monday, August 31, 2015 - link

    That's why I'm still on nehalem, overclocking an x5650 is much more fun than this pay a premium to overclock crap that intel has been feeding us. Reply
  • SanX - Saturday, August 29, 2015 - link

    Ian, add at least 4790k at 4.5-4.8GHz for us to see how bad new processors actually are Reply
  • V900 - Saturday, August 29, 2015 - link

    Isn't this right about the usual time an AMD troll jumps in to tell us how you can overclock Kaveri to 5 Ghz, and you don't even need an aircooler or anything! Reply
  • Oxford Guy - Sunday, August 30, 2015 - link

    Who is the one trolling? Reply
  • SanX - Saturday, August 29, 2015 - link

    If Intel by moving to 14nm (with its potentially twice smaller surface area versus 22nm) made mainstream octacores overclockable like 4770k/4790k i'd be interested. Otherwise it is hard to see any progress at all. Shame, even cellphones are octacores. Reply

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