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
Turbo Boost Max 3.0 (TBM3), aka Turbo Boost Max or Turbo Boost 3.0
When Intel released the enterprise focused Broadwell-EP Xeon CPUs, there were a few features added to the platform over the previous Haswell-EP generation. One of these has come through to the consumer parts, though in a slightly different form.
For Broadwell-EP, one of the new features was the ability to have each core adjust the frequency independently depending on AVX or non-AVX workloads. Previously when an AVX load was detected, all the cores would reduce in frequency, but beginning with BDW-EP now they act separately. Intel has taken this enterprise feature and expanded it a little into a feature they're calling ‘Turbo Boost Max 3.0’.
Turbo Boost 2.0 is what Intel calls its maximum Turbo or ‘peak’ frequency. So in the case of the i7-6950X, the base frequency is 3.0 GHz and the Turbo Boost 2.0 frequency is 3.5 GHz. The CPU will use that frequency when light workloads are in play and decrease the frequency of the cores as the load increases in order to keep the power consumption more consistent. Turbo Boost 2.0 frequencies are advertised alongside the CPU on the box - TBM3 will be slightly different and not advertised.
TBM3, in a nutshell, will boost the frequency of a single CPU core when a single-threaded program is being used.
It requires a driver, similar to Skylake’s Speed Shift feature (which is not in Broadwell-E), which should be distributed in new X99 motherboard driver packages, but will also be rolled out in Windows 10 in due course. It also comes with a user interface, which might make it easier to explain:
Each of the cores in the processor can be individually accessed by the OS with the new driver, and the cores will be rated based on their performance and efficiency as they come out of Intel. In the image above, Core 9 is rated the best, with Core 0 at the bottom. This means that for TBM3, the driver will primarily use Core 9.
When enabled, TBM3 will activate in two modes: either the foreground application, or from a priority list. For the foreground selection, when the software detects a single threaded workload in play, it will attempt to pin the software to the best core (similar to changing the affinity in task manager to one core), and then boost the frequency. In priority mode, the application will look for any application on the left-hand panel (which has to be added manually). If an application with higher priority is present, then the software will unpin the current software and take the higher priority one and pin that instead.
When pinned, the software will boost the frequency of that core only. The only question now is how much is the boost, and what is the effect on performance? Unfortunately, both of those questions have bad answers.
Intel refuses to state the effect of TBM3, saying that ‘each CPU is different and could boost by different amounts’. Now, you might think that makes sense. However…
Turbo Boost Max 3.0 has to be supported by the motherboard manufacturer in the BIOS. The TBM3 settings have to be set in the BIOS, which means that the usefulness of such a feature is actually down to the motherboard manufacturers. But they know how to do it right, right? Well, here’s where it can get worse.
On the MSI motherboard we used for most of our testing, Turbo Boost Max 3.0 was disabled by default in the BIOS. We asked about this, and they said it was a conscious decision made by management a couple of weeks prior. This makes TBM3 useless for most users who never even touch the BIOS. That sounds good, right?
Well, the BIOS also sets how much the CPU can boost by. So ultimately it doesn’t matter how much the CPU might like to boost in frequency, the system will only boost by the amount it says so in the BIOS, which is set by the motherboard manufacturer. In the case of the MSI BIOS, it was set to ‘Auto’. In my case, ‘Auto’ meant a boost of zero, despite the MSI BIOS ‘suggesting’ 4000 MHz. I had to manually set Core 9 to a 40x multiplier. Then it worked.
All in all, TBM3 was only enabled after I changed two settings and specifically setting the correct core in the BIOS. For me, this isn’t a global feature if that is the case. That’s not to mention how Multi-Core Turbo also comes into the mix, which still works with Turbo Boost 2.0 speeds by default. Based on what we've seen, it would seem at this time that TBM3 isn’t being readily embraced at this time.
It should be noted that we also had one of the new ASUS motherboards in for testing, however time was too limited before leaving for Computex to verify if this is the case on the ASUS motherboard as well. ASUS has told me that they have/will have a software package that enables TBM3 to be applied to multiple cores at once, whereas the Intel software will only accelerate a single program. It should be interesting to test.
The Reviewers Problem With Turbo Boost Max 3.0
In the options menu for TBM3, there are two primary options to take note of. The first is the utilization threshold, which is the % at which the software will take control of the single threaded application and pin it to a core. By default, this is set at 90%.
The other option is where a dilemma will be faced. It is the evaluation interval, or the period of time between checks that the software makes in order to accelerate a program. The version of the software we had started with a value of 10 seconds. That means if the software package starts one second or nine seconds into a benchmark run, it can affect the score. The answer here would be to make the evaluation interval very small, but the software only has a one-second resolution. So for benchmarks that run for only a few seconds (anyone benchmarking wPrime or SuperPi, for example), might either fail to be accelerated if the evaluation window is set at default, or only slightly when set at one second.
As you can imagine, if a reviewer does not know if TBM3 is enabled or not, there may be some odd benchmark results that seem different to what you might expect. It should be noted that because of the BIOS issue and the potential for motherboard manufacturers to do something different with every product, we ran our benchmarks with TBM3 disabled, and readers should check to see if reviewers specify how TBM3 is being used when data is published.
Package Differences: It’s Thin
When the Skylake mainstream platform was launched, it was noted that the processor packages and substrates were thinner compared to the previous generation. It would appear that Intel is using the same packaging technology for Broadwell-E as well.
On the left is the Haswell-E based Core i7-5960X, and on the right is the Broadwell-E based Core i7-6950X. Both of these platforms use a FIVR, the Fully Integrated Voltage Regulator, which Intel equipped on this microarchitecture in order to increase power efficiency. Usually the presence of the FIVR would require additional layers for power management in the package, but it would seem that Intel has been optimizing this to a certain extent. Each individual layer is certainly thinner, but it is likely that Intel has also reduced the number of layers, though my eyes cannot discern the resolution needed to see exactly how many are in each CPU (and I don’t have a microscope on hand to test).
A couple of questions will crop up from readers regarding the thinner package. Firstly, on the potential for bending the package, especially in regards to a minor story on Skylake where a couple of CPUs were found to have bent when under extreme cooler force. As far as Intel is aware, Broadwell-E should not have a problem for a number of reasons, but mostly related to the dual latch socket design and socket cooler implementation. Intel’s HEDT platforms, from Sandy Bridge-E on, have been rated as requiring 30-40% more pressure per square inch then the mainstream platforms. As a result the sockets have been designed with this in mind, ensuring the pressure of the latch and cooler stays on the heatspreader.
The other question that would come to my mind is the heatspreader itself. Intel has stated that they are not doing anything new with regards to the thermal interface material here compared to previous designs, and it is clear that the heatspreader itself is taller to compensate for the z-height difference in the processor PCB.
If we compare the ‘wing’ arrangement between the Haswell-E and Broadwell-E processors, Intel has made the layout somewhat more robust by adding more contact area between the heatspreader and the PCB, especially in the corners and sides. One would assume this is to aid the thinner PCB, although without proper stress testing tools I can’t verify that claim.
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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)