The Skylake-X Mess Explored: Thermal Paste And Runaway Power

Manual Overclocking & Conclusion

The Motherboard Manufacturers’ Duty

Ultimately, we’re looking at power consumption numbers similar to some high-end graphics cards when we start messing with Skylake-X. AMD’s FX-9590X doesn’t even come close to these results, if that means anything to you. This means motherboard manufacturers need to start spending money on better components and cooling solutions to take care of those components. Otherwise, long-term reliability will be hard to guarantee. Ultra-durable and military-class components don't have to be exclusive to top-end products; they can bolster mid-range platforms, too.

Motherboard manufacturers could have and should have known that Intel's Skylake-X CPUs would consume power indiscriminately, in spite of the company's laughably low TDP specifications. Everyone has access to Intel's datasheets, not just us.

Different motherboards will be affected to different degrees by our findings, and the one we tested isn't a flagship model by any means. You shouldn't generalize our results to mean there's an impending VRM-related disaster hanging over the heads of all Skylake-X owners. Boards from every manufacturer across a number of price points need to be tested before such a claim can be made. What we do know is that, although the problem originates under Intel's heat spreader, fault is also found with motherboard manufacturers as well.

We already have a high-end motherboard on its way from the same manufacturer, and we'll report our findings after running the same battery of tests.

Overclocking For Power, Not Frequency

Although we ultimately wanted to explore the CPU's and VRM's cooling problems, we were also curious about Skylake-X's remaining overclocking headroom. Rather than targeting specific clock rates, though, we systematically pushed our Core i9-7900X to 250W and then to 300W. That's all its technical specifications allow for, so that’s where we stopped.

Observation #5: We aren't here to destroy our hardware. Enthusiasts need to decide on their own if they're willing to risk $1000 components. Power users on the overclocking circuit typically have processors provided to them, so a single CPU isn’t something to lose sleep over. We, however, along with most folks only have one sample to work with. Failure would be far more devastating. Technical specifications and limits are there for a reason, and in this case we're honoring them.

Let’s start with the massive 250W, which Intel's Core i7-5960X reached at 4.8 GHz back when we reviewed it. Core i9-7900X gets there at 4.5 GHz under Prime95, and at 4.6 GHz with LuxRender in a console loop. Other applications yield better results, depending on their workloads.

Intel’s Core i9-7820X doesn’t really do any better: it’s separated from the larger 10-core processor by only 20W when performing the same tasks. If you're overclocking this way, pay close attention to wattage and adjust the clock rates and voltages via trial and error, depending on the applications you use.

250W & The Limits Of Normal Water Cooling

In our scenario, we occasionally hit the 270W mark, which probably represents this specific motherboard’s limit. In other words, MSI’s X299 Gaming Pro Carbon AC stays approximately 30W below the maximum wattage allowed by Intel’s technical specifications. The problem is that most custom water-cooling setups aren't able to keep the die and package cool enough to prevent throttling. Even with a water temperature of 30°C, it wasn't possible to run under load for more than 10 to 15 minutes without thermal issues.

The CPU throttles before the motherboard’s VRM has a chance to hit 100°C. This means that all of the flashy plastic parts on top of the VRM are basically useless, since the CPU throttles before they can do anything. Once again, here’s the video to go along with the graph:

Intel Core i9-7900X Heating Up with 250 Watts on Vccin

Intel’s Limit: 300W & The Mild Scent Of Disaster

Now, can we hit the 300W mark without our system dying a fiery death using our trusty Alphacool Eiszeit 2000 Chiller? To make a long story short: yes, we can...for about 10 minutes. After that, the voltage converters hit 105°C and the CPU’s frequency drops to 1.2 GHz with a power consumption of 70W. That’s enough for the components to recuperate quickly, after which the whole sequence starts over, resulting in an endless loop.

So close, but no cigar. Then again, who else out there uses an Alphacool Eiszeit 2000 Chiller? Most folks won't be able to push their system to the brink of death like this without delidding their processor first. Even with our high-end cooling solution, the Tpackage measurement exceeds 100°C, while the cores run at 94°C and up. This can’t be called sufficient cooling by any stretch of the imagination.

Our video shows the motherboard and its hot-spots once again. In spite of the 105°C you'll see in a few places, none of the components are in danger, since none of the ones that have a temperature limit below this number are affected. That’s at least something.

Intel Core i9-7900X Heating Up with 300 Watts on Vccin

At least we can rest easy knowing that few power users will ever take their Skylake-X CPUs this far. And if your job involves testing high-end hardware, you shouldn't have a problem locating a suitable motherboard able to handle the heat.

Conclusion

So, what’s the bottom line? Intel is pushing the envelope once again with a factory-overclocked Xeon processor doing double-duty as a high-end desktop masterpiece. We're getting the sense, though, that the revered Core architecture can't be pushed much further. Everything works well enough this time around, at least. And if Intel hadn't chickened out and put thermal paste between its die and heat spreader, there might have been a happier ending for everyone involved in this story.

As it stands, even a custom water-cooling loop has to throw in the towel at 250W, long before most motherboard voltage converters hit their limits. Under normal operating conditions, the CPU, and not the motherboard, always throttles first.

Nevertheless, motherboard manufacturers aren’t blameless when it comes to the issues we encountered at launch and continue battling today. Using more thermodynamic expertise and less flashy plastic pieces would have paved the way for brawnier motherboards at the same price points. This would have ended the speculation before it even started. Anything designed to be just good enough always leaves you with a bad aftertaste, particularly since you never know when you might need a little extra headroom.

[Editor’s Note: We reached out to Intel for commentary back in March after  a number of readers speculated about Intel’s choice of thermal paste on Kaby Lake, and in response to our article De-Lidding And Overclocking Core i7-7700K With Water And LN2. We did not receive any technical or marketing explanations at the time, but we have followed up again related to the Skylake-X issue, and we will update this article if and when we receive a reply.]

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138 comments
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  • You guys don't get it??? I talked to some people who got 6 core of Skylake-X and they were able to push CPU up to 4.6Ghz on all cores where temperatures were fine under Prime. Again temperatures were much lower in anything else. In my opinion Prime is rather unrealistic stress test, not to say useless crap proving nothing. I am not defending Intel but you all approached this problem with a wrong assumption.

    With 7900X which is still built using 14nm fabrication process, there is no in hell you are going to be fine with temperatures on overclocked 10/20 cores. That's just too many of them to keep them cool.

    If someone gets 10/20 CPU i would not push more than 4Ghz. That is a max realistic clock speed for such CPU, with 8 Core you will be better but i'd say the best thing to buy is actually 6/12 Core which can easily run at @4.5Ghz.

    People don't play Prime or any other similar >Mod edit: keep it clean<test. People game, do programming, stuff where you will never see CPU showing overheating issue. And again keep 10/20 at 4.0Ghz max. Honestly you won't gain a thing running at 4.4Ghz.
  • Also i might want to add is to wait for second iteration of x299 boards. The first batch is a joke from cooling point of view. Evga is one of the companies which will get it right. X299 need copper based cooling for VRM and chipset and also 2x8pin CPU connectors with recommended PSU of 1000W+. That's how i would run x299 setup.
  • AgentLozen
    Freak777Power said:
    You guys don't get it??? I talked to some people who got 6 core of Skylake-X and they were able to push CPU up to 4.6Ghz on all cores where temperatures were fine under Prime. Again temperatures were much lower in anything else. In my opinion Prime is rather unrealistic stress test, not to say useless crap proving nothing. I am not defending Intel but you all approached this problem with a wrong assumption.


    What's wrong with using Prime? It does a good job of testing the thermal limits of a CPU. You wouldn't test the limits of a weight lifters strength with 5 pound dumb bells. You need to go all out.

    You say that the author of this article approached this problem with a wrong assumption. Do you think that there's nothing noteworthy of Skylake X's thermal performance?

    I think this article did a good job of pointing out the glaring flaws of Skylake X. The conclusion is really interesting: "We're getting the sense, though, that the revered Core architecture can't be pushed much further." That gives me chills. I never thought I'd see the day when Core hit its limits.
  • rothbardian
    496490 said:
    The conclusion is really interesting: "We're getting the sense, though, that the revered Core architecture can't be pushed much further." That gives me chills. I never thought I'd see the day when Core hit its limits.


    It's a chilling conclusion indeed. It all points out to AMD's multi-die, multi-ccx architecture of Ryzen Threadripper being supperior to Inte's Core on all counts.
  • Wisecracker
    Good job -- Thank you for the in-depth analysis.

    BUT (you knew that was coming ;) right?), I question the need to call-out motherboard OEMs. I agree with the comments regarding unnecessary 'Bling' but they clearly feel they are delivering what the market demands in that regard ...

    It seems off-kilter to focus/blame board components and OEMs at the top of your conclusion page, and not really Chipzilla, while noting Sky(lake-X)-rocketing heat/power beyond that of the previous-gen 32nm AMD FX-9590 (constantly derided since its introduction as a power-hungry 'heater').

    Know what I mean, Vern?

    edit: How could I have misquoted Earnest!
  • FormatC
    To be honest, this was translated in absolute hurry over the weekend and sounds now (without my lyrics) a bit harsh. But one thing is fact: without all this kiddish plastic crap, covering the cooler surface, it might work a lot better. As I wrote on page One (intro); it is a causal chain and at the begin is the CPU.
  • AgentLozen
    Quote:
    See what I mean, Vern?


    I know its petty, but isn't the line, "Know what I mean?" We're talking Jim Varney, right? Haha.
  • JamesSneed
    This article spells out the points why I decided to build a Ryzen based system. I waited for Skylake-x and the thermals / power are just way to off the charts for the little extra performance. I could not be happier with the Ryzen 1800x build and yes I know I paid more for something you can get in the 1700 and OC it. I certainly agree anyone needing more than 8-cores should wait on Threadripper as it really has a chance to take Intel on performance due to these very same thermal / power issues in the i9 which means the higher core counts won't hit the same frequencies.
  • JamesSneed
    482859 said:
    To be honest, this was translated in absolute hurry over the weekend and sounds now (without my lyrics) a bit harsh. But one thing is fact: without all this kiddish plastic crap, covering the cooler surface, it might work a lot better. As I wrote on page One (intro); it is a causal chain and at the begin is the CPU.


    I agree, they should be called out when form causes a hit to function. I didn't find it harsh at all. Motherboard makers are all enamored right now with shiny pretty and are loosing sight on quality. I don't care if it has LED's or looks "cool" but never should that be at the expense of the motherboards main function.
  • mrjhh
    Power consumption and TDP are only marginally linked. Maximum power consumption relates to the maximum the chip could possibly use, while TDP is what a heat sink needs to be able to dissipate. The chip will thermally throttle if the maximum power consumption extends for long, but this condition should not happen in normal usage. But, if one uses all execution units within the processor at the same time, one will hit maximum power consumption at least momentarily. But, it's hard to keep all execution units running all the time, as there are typically cache misses which slow the processor, as well as software inefficiencies preventing running all execution units all of the time. Normally, that would put the average power consumption within TDP limits. Unusual use cases could exceed TDP, and cause thermal throttling.
  • 496490 said:
    Freak777Power said:
    You guys don't get it??? I talked to some people who got 6 core of Skylake-X and they were able to push CPU up to 4.6Ghz on all cores where temperatures were fine under Prime. Again temperatures were much lower in anything else. In my opinion Prime is rather unrealistic stress test, not to say useless crap proving nothing. I am not defending Intel but you all approached this problem with a wrong assumption.
    What's wrong with using Prime? It does a good job of testing the thermal limits of a CPU. You wouldn't test the limits of a weight lifters strength with 5 pound dumb bells. You need to go all out. You say that the author of this article approached this problem with a wrong assumption. Do you think that there's nothing noteworthy of Skylake X's thermal performance? I think this article did a good job of pointing out the glaring flaws of Skylake X. The conclusion is really interesting: "We're getting the sense, though, that the revered Core architecture can't be pushed much further." That gives me chills. I never thought I'd see the day when Core hit its limits.


    Because it is unrealistic, and finding thermal limit is just pointless. Go and read Intel specs sheet and tells you about this processor thermal limit. We really don't need any test to show such thing. Tomshardware spent pages of writing something pretty much everyone knew about if you were to read Intel specs. And even if you did not logically anyone can conclude that using same 14nm fabrication process won't play in favor in term of overclocking and heat.

    Again 10/20 is a lot of cores and to cool that with 4.0 Ghz+ clock speed, good luck with that.

    You people think that AMD Thread Ripper will run cooler, it will with 2.4Ghz clock speed. Seriously i had chance to play with every iteration of Xeon and AMD counter part CPU and you people have no idea of what you are talking about. 18 Core Broadwell-E or Haswell-E CPU for example is hell of task to cool down therefore those CPU run <3.0Ghz speed. We didn't hit any limit with Core CPU, but with what's possible using 14nm fabrication process. The fact that you can even overclock 10/20 to 4.4Ghz with such core count and complexity CPU package itself carries is AMAZING compared to AMD Ryzen which can't hit anything above 4.0Ghz with rather high temperature.

    You people get your fact straight.
  • FormatC
    If you read the intro between the lines, this test is a kind of answer to a YT video that was telling us, that all motherboard makers failed. I only tried to show, that we have headroom enough, to use this CPU as is without any kind of limitations. Only manually OC is able to bring it in trouble. :)
  • kinggremlin
    Prime 95 is the cpu equivalent of furmark. It's basically a power virus that does not represent the power usage of any other program you can come up with including other stress test programs. Intel implemented automatic throttling for their igpu's when furmark was detected. I wouldn't be surprised to see the same thing for prime95 on their cpu's.

    The bodybuilder analogy is idiotic. The prime95 equivalent would be to require grocery stockers to bench 500lbs as part of the hiring process to demonstrate the strength necessary to lift grocery products on the shelf. They will NEVER have to lift that much making it a meaningless and unrealistic test.
  • Phil_52
    Would love to hear the reviewers thoughts on how to setup these boards to de-clock the CPU in a way that reduced the head issues without too much damage to normal performance. I have just ordered a X299 setup and am more interested in the chipset features (PCI Lanes, Multi M.2 support etc) than the RAW horse power of the CPU.. So the question is, if I do the opposite of nature and under-clock... can I get a good balance ?
  • FormatC
    Simply use the mainboards functions to limit the wattage and / or play with Vcore and Vccin. I will also write a follow-up in both directions when I get a better mainboard.
  • bloodroses
    2070440 said:
    496490 said:
    The conclusion is really interesting: "We're getting the sense, though, that the revered Core architecture can't be pushed much further." That gives me chills. I never thought I'd see the day when Core hit its limits.
    It's a chilling conclusion indeed. It all points out to AMD's multi-die, multi-ccx architecture of Ryzen Threadripper being supperior to Inte's Core on all counts.


    Once/If Threadripper is able to clock higher and have a faster IPC, then AMD can talk about being superior. Looking at the leaked specs so far, neither appears to be true. While it's great that AMD is back in the game again and finally giving Intel competition, they are no means superior outside cost/value and core count.

    To give a comparison, Threadripper supposedly will have a tdp of 125-155w, with the highest topping out at 4.1ghz boost. The 10 core equivalent has a 125w and 4ghz boost.

    http://wccftech.com/amd-threadripper-1998x-and-threadripper-1998-processors-x399-x390/

    Chances are these will run quite hot as well and are huge in size. These 2 links show the size of the die and coolers needed:

    https://www.lowyat.net/2017/133239/computex-2017-noctuas-amd-threadripper-cpu-cooler-massive/

    http://www.pcgamer.com/amds-threadripper-is-huge-with-an-equally-large-socket-and-cooler/


    Intel's I9-7900x has a tdp of 140w, with a 4.3ghz boost. Their die size is still roughly the same as that of the rest of their core lineup in comparison to Threadripper's monstrous size. The biggest mistakes Intel made was the thermal paste (as the author mentioned) and while not really a mistake; trying to cram too much into a tiny space for their socket.
  • JamesSneed
    1069610 said:
    2070440 said:
    496490 said:
    The conclusion is really interesting: "We're getting the sense, though, that the revered Core architecture can't be pushed much further." That gives me chills. I never thought I'd see the day when Core hit its limits.
    It's a chilling conclusion indeed. It all points out to AMD's multi-die, multi-ccx architecture of Ryzen Threadripper being supperior to Inte's Core on all counts.
    Once/If Threadripper is able to clock higher and have a faster IPC, then AMD can talk about being superior. Looking at the leaked specs so far, neither appears to be true. While it's great that AMD is back in the game again and finally giving Intel competition, they are no means superior outside cost/value and core count. To give a comparison, Threadripper supposedly will have a tdp of 125-155w, with the highest topping out at 4.1ghz boost. The 10 core equivalent has a 125w and 4ghz boost. http://wccftech.com/amd-threadripper-1998x-and-threadripper-1998-processors-x399-x390/ Chances are these will run quite hot as well and are huge in size. These 2 links show the size of the die and coolers needed: https://www.lowyat.net/2017/133239/computex-2017-noctuas-amd-threadripper-cpu-cooler-massive/ http://www.pcgamer.com/amds-threadripper-is-huge-with-an-equally-large-socket-and-cooler/ Intel's I9-7900x has a tdp of 140w, with a 4.3ghz boost. Their die size is still roughly the same as that of the rest of their core lineup in comparison to Threadripper's monstrous size. The biggest mistakes Intel made was the thermal paste (as the author mentioned) and while not really a mistake; trying to cram too much into a tiny space for their socket.


    We will see soon enough on Threadripper. I really don't think they will run hot as you do. They have a large heat spreader with the dies underneath spaced out and should be soldered. This should make for lovely cooling capabilities even with air. The 16+ core parts of AMD and Intel are where it gets really interesting seeing how Intel deals with the heat of a CPU that is 60-80% more cores than the 7900x.
  • nyannyan
    Heat is going to be a real problem when the 18 core SKUs come out regardless of Prime95. There are other AVX heavy use cases you know and the headroom will decrease with each additional core. Right now I'm quite satisfied that I went with Broadwell.
  • Aspiring techie
    I can only imagine what will be needed to cool the 18 core variant...
  • techy1966
    Great Article Thank you I found it very interesting and it answered a lot fo questions for me. I think both Intel and the main board makers are at fault. Intel because they rushed these CPU's out and used thermo paste instead of soldered heat spreaders. I also think they have reached the limit of their 14nm process and need to shrink it again.

    Main board makers at fault for as you stated putting all that plastic bling bling on the boards because they think consumers think it is cool. Only teens and 20 something find that cool the rest of us just want fully working boards that do as advertised out of the box. If the plastic bling bling & RGB lighting effects the board performance it needs to go simple as that.
  • the nerd 389
    For your motherboard reviews with this CPU, might I suggest that you look up the rated lifetime of the PWM caps?

    If those are 5k caps, they'll only last 5000 hours at their rated temperature. Lifetime usually doubles for each 10C under that rating.

    These CPUs often end up in entry level workstations. If the intended usage pushes the caps to 75 C, and they are the more common 5k/105C, then conventional wisdom indicates that 10% of the caps should fail by the 40,000 hour mark. In those cases where the CPU is fully loaded most of the time, this will occur 4.5 to 5 years of age. This means that there isn't much room for mistakes in the motherboard layout, case design, or airflow requirements. It's something that potential consumers should take into account if they want to get the most out of this platform.

    I'd have to check in more detail to give any estimates for the MOSFET lifetime, but that's another factor to account for if longevity is a priority.
  • chaosmassive
    well done Intel, I applaud you !
  • FormatC
    983009 said:
    For your motherboard reviews with this CPU, might I suggest that you look up the rated lifetime of the PWM caps? If those are 5k caps, they'll only last 5000 hours at their rated temperature. Lifetime usually doubles for each 10C under that rating.
    Suggest it Thomas, he makes the mainboard reviews here. The idea is not bad to see deeper into the tech. I'm testing here VGA boards and I disassemble all.
  • Nintendork
    Intel repeated the P4 Prescott mistakes, they never wanted more than 10 cores for HEDT, not with Zen blowing them in performance per watt, power consumption and temps they forced their HEDT out of reasonable limitis to look good on benchmarks.

    Overaggressive turbo clocks, high power consumption, unacceptable temps, and this is only the 10core...

    Since they dropped the price more than they wanted now they cheap out $1 from solder to toothpaste.