The Intel Broadwell-E Review: Core i7-6950X, i7-6900K, i7-6850K and i7-6800K Tested
by Ian Cutress on May 31, 2016 2:01 AM EST- Posted in
- CPUs
- Intel
- Enterprise
- Prosumer
- X99
- 14nm
- Broadwell-E
- HEDT
Load Delta Power Consumption
Power consumption was tested on the system while in a single MSI GTX 770 Lightning configuration with a wall meter connected to the OCZ 1250W power supply. This power supply is Gold rated, and as I am in the UK on a 230-240 V supply, leads to ~75% efficiency > 50W, and 90%+ efficiency at 250W, suitable for both idle and multi-GPU loading. This method of power reading allows us to compare both the power management of the BIOS and the board's ability to supply components with power under load, and includes typical PSU losses due to efficiency.
Each of the Broadwell-E SKUs are rated at 140W, however they vary between 6 cores and 10 cores and with different frequencies. Normally one would assume that the core/frequency ratio would be adjusted to match TDP, but ultimately using more cores can consume more power. We see a distinct increase in power consumption moving up the product stack.
Prime95 Core Loading
For this review, we also looked into peak delta power draw when varying the number of cores using Prime95’s mode for peak power consumption. Prime95 identifies cores with multiple threads and adjusts its loading/pinning accordingly.
Broadwell-E Overclocking
Methodology
Our standard overclocking methodology is as follows. We select the automatic overclock options and test for stability with PovRay and OCCT to simulate high-end workloads. These stability tests aim to catch any immediate issues with memory or CPU errors.
For manual overclocks, based on the information gathered from previous testing, we start off at a nominal voltage and CPU multiplier, and the multiplier is increased until the stability tests are failed. The CPU voltage is increased gradually until the stability tests are passed, and the process repeated until the motherboard reduces the multiplier automatically (due to safety protocols) or the CPU temperature reaches a stupidly high level (100ºC+). Our test bed is not in a case, which should push overclocks higher with fresher (cooler) air.
Overclock Results
Due to time constraints we were only able to overclock the i7-6950X using the MSI X99A Gaming Carbon motherboard. MSI has improved its overclocking options as of late on the Z170 platform to make it easier to use, but our BIOS did not have those most recent updates, particularly for load line calibration. However, our sample hit 4.1 GHz at 1.30 volts before the OCCT load temperatures were prohibitive to move up any further. We saw similar things when testing the mainstream Broadwell parts with Iris Pro, which shows that this sort of overclocking performance might be indicative of the silicon itself.
That being said, speaking with our contacts at various motherboard manufacturers, we're told that 4.1 GHz is a reasonably average processor result for Broadwell-E. Some processors will hit 4.3 GHz on air at around the same voltage, whereas others need up to 1.4 volts, and thus results will depend on the cooling setup used or the thermal characteristics of the silicon. I have also been told that AVX is a different story: for any peak frequency attained normally, AVX overclock stable frequencies will be around 200-300 MHz lower.
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Flunk - Tuesday, May 31, 2016 - link
DX12 actually uses the CPU more efficiently so it should make every LESS CPU constrained, not more so.willis936 - Tuesday, May 31, 2016 - link
Well if you want to toss four channels of memory and 28 pcie lanes out the window and just talk about gaming then you should probably keep it in your head that anyone buying these processors over xeons will be overclocking them. You'll likely get identical single threaded performance on the six core parts to the four core parts but just have 2 more cores. If you say more cores doesn't matter in gaming well idk why everyone (including anandtech) is saying this. I play csgo and bf4 @ 1440p120 on a 770/4790k@4.5GHz and while I'm still GPU limited I see all 8 threads get over 70% usage regularly. I have no doubt that even this 4 core single threaded performance king will bottleneck a 1080 in some cases. Intel has slowed down in performance increases and GPUs haven't. The old talk of "you'll always be CPU limited" shouldn't be treated as dogma. Oh and anandtech should consider changing their CPU gaming benchmarks. It's not super helpful to see a bunch of data that shows a dozen CPUs at a dozen scenarios that are all GPU limited. It's not hard to choose realistic CPU limited scenarios.bogda - Tuesday, May 31, 2016 - link
It is difficult now and it has always been difficult finding meaningful, high end, CPU limited gaming benchmarks (unless you are working in Intel marketing/sales). Nobody buys $1000+ processor to run games at 720p.Anybody thinking about buying high end processor for gaming, after seeing meaningful gaming benchmark, should think twice.
P.S. You probably wanted to say "... you will always be GPU limited should not be treated as dogma".
jacklansley97 - Tuesday, May 31, 2016 - link
These aren't meant for gamers anyway. HEDT has always been aimed at content creation, development, and calculation. I don't know why anyone thinks it's a revelation that these chips don't perform better than a quad core for gaming.Impulses - Tuesday, May 31, 2016 - link
Even then, you need to study your needs carefully... For basic photo/Lightroom tasks clock speed actually matters a decent amount and not a lot of tasks scale super well beyond 4 cores... Obviously for things like video encoding more cores will make a huge difference.joex4444 - Tuesday, May 31, 2016 - link
For gaming, no, but that's the thing: PCs can do so much more than just play games.unityole - Tuesday, May 31, 2016 - link
wanted to see more core per core IPC from 6800/6850k vs 4960x and also 5960x vs 6900k. not just because of technology changed also IPC gain from using TB3.0 which probably minimal.Ian Cutress - Tuesday, May 31, 2016 - link
We covered IPC in both our Broadwell and Skylake mainstream desktop reviews:http://www.anandtech.com/show/9483/intel-skylake-r...
landerf - Tuesday, May 31, 2016 - link
That broadwell has edram. This one doesn't.The two things I and a number of others wanted to see from this review were IPC and overclocking for the whole range, as we've already seen from leaks the 10 core was a bad clocker but a lot of people had high hopes for the lower core models.
Ian Cutress - Tuesday, May 31, 2016 - link
That's a fair point. After Computex blows over I'll look into running Broadwell-E with dual channel memory similar to those tests.