The Super-binned 9990XE perfectly illustrates current and future issues with power draw and cooling

The 9990XE made headlines in April of this year for being an Auction-Only part as well as Intel’s fastest most powerful CPU to date. At International Computer Concepts we’ve tested a few of these at their Manufacturer’s settings (5.0GHz, Default voltages) and found that they are nearly impossible to keep stable without a beefier cooler (We normally use a 360mm radiator + heatsink for general testing). We were able to push these past their 5.0 spec with a 420mm radiator equipped with a monoblock. Some reviewers were able to do this with bigger watercoolers and raising the thermal throttling temperature limit over 105C. This is just normal watercooling, not chilled, no reservoir, no phase change, et cetera. That is why the testing below is with prime95 version 26.6. The 5.0GHz you see on the 9990XE would need to run at ~4.8GHz for AVX and ~4.6GHz for AVX2 with similar cooling solutions.

So the trick we needed to accomplish was how to get acceptable speeds on this power hungry monster with a 360mm radiator. 

First, we tested them at default settings with mPrime v26.6 (prime95). SSE testing is the best way to test for max turbo-all core out of the box to get a handle on what settings will be needed for the more intense instruction sets like AVX, AVX2, AVX-512. It took a 420mm radiator and monoblock before being able to keep the temperatures across all cores under 104C, which actually handled them quite well keeping them under 95C for 24 hour sessions. Even that is unacceptable for 24/7 use to some overclockers who prefer to keep temps under 85C max on stress tests for their daily-use PCs. The 360mm radiator and heatsink couldn’t do this without throttling – or crashing.

  • 9990XE 14-core running with a 360mm water cooler.
  • Undervolted from default voltage of 1.38V.
  • One core crash after 20 minutes, most cores over 100C.
  • A few of the 9990XEs can handle the 5.0 SSE undervolted between 1.28-1.32V for 24hours but this one was not one of them

At 5.0GHz on 14 cores this was already faster than any current CPU on water cooling that you could find for HEDT. The downside of this was the Cache clock speed sitting at 2.4GHz default, much like the Skylake-X Refresh CPUs, if Cache performance is what you’re looking for this might not be the best option. The default voltage when loading optimized settings and enabling turbo was reading between 1.36V and 1.45V on over 5 of these. That’s the same type of voltage you will see at default and on high overclocks of 4 to 6 core CPUs, so you can understand what kind of heat is being created here. You may have seen some reviews online or videos testing these showing how hot they get with regular cooling.

So all of the 9990XEs we tested on were able to pass 5GHz without throttling (throttle temp set to 105C) on the 420mm radiator granted temperatures were still higher than what most are comfortable with. Most of them can do it on the 360mm but almost always require undervolting.

The big question that comes with this is will cooling be able to keep up with what Intel is pushing out? We’ve seen some water coolers claiming TDP capacities of over 500W now but we’re starting to see CPUs able to draw 500-800W with multiple CPUs available now with 255W+ TDPs. It should als obe noted that the TDP listed for these is for the base clock speed – not the turbo speeds. So that TDP is much higher when attempting to run at turbo or higher all core. That’s not the only issue though as we are also seeing motherboards coming with 1 fan, 2 fans, even 4 fans on the VRMs (Voltage Regulator Modules used to help control power sent to the CPU). With Skylake-X and Skylake-X Refresh VRMs became a hot topic where many saw underperforming CPUs and didn’t know why and others pushing that motherboards were being sent as final products with the major fault of not having capable heatsinks for the VRMs – those first models getting the bandaid treatment of receiving small mountable fans to put over them.

Soon enough all you’ll be able to see on a motherboard is heatsinks and pipes covering all of the available retail space, and coolers taking up half of the space in your case/chassis.I don’t think we’re headed towards a future where desktops are sporting phase change coolers as an accepted norm, but something definitely has to give and pretty soon.

– Betim Begolli