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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Witek - Thursday, June 16, 2016 - link
@rodmunch69 - Yeah. I also almost 4 years on 3930K (at 3.2GHz->4.2GHz), which I got for something like 350$ at the time. And I still do not see anything better in similar price bracket. x86 arch is a shit, with limited instruction issue, substandard compilers targeting generic cpus, and power hungry circuits trying to workaround the arch limitations.The prices on these new CPUs are shit, and Intel do that because they do not have competition in high performance x86 market right now. I understand making 14nm chip is more costly than previous generations, but eh, still it is crazy. There is no point of using 14nm for desktop if it doesn't provide substantial performance boost or power saving, at similar price. I am seriously looking into ARM64, Power8, MIPS and other architectures (especially high core counts, or ones still in developement - like Out of the Box Computing Mill CPU), that can break this trend (at least on Linux). SPARC looks like highest performance at the moment, but the prices are crazy as hell. Intel Phi is also interesting for paralellized workloads, but the price is still very high (due to the smaller target market).
Zen will help bring these prices into check. 16 core Zen (32 threads) at 1000$ would be awesome, and will bring all these Intel i7 cpus prices down substantially too.
vivs26 - Tuesday, May 31, 2016 - link
Looking at single threaded and multi threaded performance cant help but be reminded of Amdahl's law. The performance you can extract out of your system is only as much your workload allows you to ....ithehappy - Tuesday, May 31, 2016 - link
I am still on i7 950, just with a GTX970, will it be worth it if I get the 6800K? Or shall I still wait for Skylake-E? Gaming is my main priority, and low power consumption, because mine is on nearly 24x7.rhysiam - Wednesday, June 1, 2016 - link
If all you care about is gaming, get an i7 6700K. There's almost no value proposition in these CPUs anymore unless you absolutely need more than 4 cores. Very few games have been shown to benefit from more than 4 cores at all, and the hyperthreading on the i7 6700K will be there to help if (probably when) games finally start to scale better. The single threaded performance of the 6700K is also significantly better. If you have high end graphics and a 120/144hz display, where CPU performance can sometimes start to matter, the 6700K is actually the faster CPU, and would net you higher fps than any of these overpriced Broadwell-E CPUs.The only argument you could make is that at some point in the future games might start to benefit from 6+ cores. We've already seen in gaming benchmarks of i5s vs i3s vs Pentiums that hyperthreading does a surprisingly good job at mitigating the impact of a game running more threads than you have CPU cores. There's a very good chance that the 4 Core + HT of an i7 6700K will hold its own in gaming for a long time to come. Even if that turns out to not be the case, you'd be much better off in the long run just upgrading your machine when you need it rather than sinking money into a Broadwell-E system now.
mapesdhs - Thursday, June 9, 2016 - link
Re your power consumption, if that's because you care about long term cost, then there's a lot of utility in used hw such as a 3930K. It'll give a very good boost, it's much easier to oc than the later models, it's cheap, the platform supports broad SLI/CF, and it'd take years for the slightly higher power consumption of a 4.8 3930K to wipe out the huge cost saving vs. a 3930K (BIN for 96 UKP on eBay UK atm). It'll also better exploit future improvements in game design that support more cores.If you do want something new though, then rhysiam is right, 6700K or 4790K is fine.
Or go for something inbetween, like a used 4930K (costs a bit more, but higher IPC and some other benefits over SB-E).
However, if you do want something new, then rhysiam is right, the 6700K is plenty, or indeed a 4790K.
asmian - Tuesday, May 31, 2016 - link
Quite apart from cost/performance, the key question for some is whether this last version of Broadwell has had retrofitted the SGX extensions that were introduced with Skylake. Was this feature left out as it wasn't part of the original Broadwell platform? (Preferable) lack of SGX will mean this is the last secure-from-remote-snooping Intel processor release, otherwise the last will unfortunately be Haswell/Haswell-E.Anandtech has been conspicuously silent on SGX and why this is a privacy nightmare for users, unable to monitor or detect exactly what software may be secretly running on their processors due to a by-design inability to snoop on the process in-use memory. The benign use cases usually put forward hardly outweigh the risk of mode-adoption by virii, trojans and user-snooping malware of government origin, able to obfuscate their own remote loading, which would potentially be immune from detection by any means (likely including by the AV and anti-malware industry).
For more on why SGX is of concern read http://theinvisiblethings.blogspot.co.uk/2013_08_0... and http://theinvisiblethings.blogspot.co.uk/2013_09_0...
Please confirm definitively whether Broadwell-E has SGX or not.
Jvboom - Tuesday, May 31, 2016 - link
This is so disappointing. Every time a new release comes out I come on here hoping to justify buying. The numbers just aren't there for the $$.Tchamber - Tuesday, May 31, 2016 - link
Is anyone else disappointed that a new, cutting-edge CPU consumes 10W more than my 2010 i7 970 with the same number of cores? Add to that, prices go up faster than performance does. That makes it nice to see that CPUs don't make much difference in gaming. There are plenty of features I'd like, but I can wait till Zen comes out. In all honesty, I'll probably buy Zen just to support the underdog.krypto1300 - Tuesday, May 31, 2016 - link
Man, and I'm still getting by with my workhorse 1366 platform from 6 years ago. Running a Xeon X5650 @ 3.66GHz , 16GB of DDR31866 and a GTX 970! Everything still runs great! Doom and Project Cars do 1440P @ 60fps no problem!mapesdhs - Thursday, June 9, 2016 - link
A good example that shows the continued utility of what IMO was the last really ground-breaking new chipset release. I can remember reading every review I could find at the time about Nehalem and X58. Not done that since.Btw, are you by any chance using a Gigabyte board? 8)