The Intel Skylake i7-6700K Overclocking Performance Mini-Test to 4.8 GHz
by Ian Cutress on August 28, 2015 2:30 PM EST
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.
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Impulses - Saturday, August 29, 2015 - link
Why would it make a difference? The BCLK is now decoupled from anything that would matter... It's just another tool like the ratio, one that could let you eke out an extra 50MHz or whatever if you really care to take it to the edge.Khato - Friday, August 28, 2015 - link
Two inquiries regarding future Skylake testing:1. While the initial review was intriguing in terms of actually exploring the DDR3L vs DDR4 2133 performance difference, higher DDR4 frequency testing is still absent. Will there be a memory scaling article at some point?
2. What's the point of evening including the discrete gaming benchmarks? Is there a plan to revamp this category of testing to provide meaningful data - inclusion of minimum frame rates, exploring different settings, using different games.
ImSpartacus - Saturday, August 29, 2015 - link
Yeah, it would be nice if we could get some proper frame time benchmarking.varg14 - Saturday, September 5, 2015 - link
I too would love to see High end DDR3L compared to DDR4 on skylake and if the tight timings of DDR3l are beneficial in what areas if at all.ImSpartacus - Friday, August 28, 2015 - link
I feel ridiculously shallow for asking this but could we see fewer tables that look straight out of excel going forward?Anandtech has a glassy table & graph design language. While it might be a bunch of excel templates, it still lets me suspend my disbelief a little bit more.
I can't justify my request with any tangible argument other than something "feels" off. I apologize as I understand how frustrating such feedback can be. I trust Anandtech to always be improving & setting the standard on all fronts.
ImSpartacus - Friday, August 28, 2015 - link
classy*garbagedisposal - Saturday, August 29, 2015 - link
They've used the same format a number of times before and it's pretty damn clear and easy to understand. Prettifying the excel tables on a mini article is a waste of time.ImSpartacus - Saturday, August 29, 2015 - link
You're right, this isn't an isolated issue. I didn't comment on it first time or the second time.And it's hard to tell someone who exhaustively tested numerous scenarios that they oughta spend even more time to ensure that they follow style guides and that the extra time spent won't even affect the utilitarian value of the results.
V900 - Friday, August 28, 2015 - link
Nice overview.But isn't overclocking in reality not really relevant anymore? A remnant of days gone by?
Dont get me wrong, I was an eager overclocker myself back in the day. But back then, you could make a 2-300$ part perform like a CPU that cost twice as much, if not more.
Today, processors have gotten so fast, that even the cheap 200$ CPUs are "fast enough" for most tasks.
And when you do overclock a 4ghz CPU by 600mhz or more, is the 5-10% speed increase really worth it? Most people would have been better off taking the hundreds of dollars they invested in coolers, OC friendly motherboards, etc and put them towards a better CPU instead.
Impulses - Friday, August 28, 2015 - link
There's a lot of people that just do it for fun, same way people mess with their cars for often negligible gains... Not all spend a lot on it either, I'd buy the same $130-170 mobo whether I was OC'ing or not, and I'd run the same $65 cooler for the sake of noise levels (vs something like a $30 212).