CPU Suddenly Hot Under Load

KylePolansky · December 1, 2017

Summary: CPU Temps suddenly at 95-100 degrees C at 100% load when previously only at 60-65 degrees C.

Long Story: Today I noticed my CPU fan was taking longer than usual to ramp down after being at 100% load (I run BOINC at 100% when not using the computer, and it auto-pauses when I log back in), so I checked the CPU temps and they were at 95-100 degrees C. After waiting about 2 minutes (at idle), the temps dropped down to 25-30 degrees C. I ran Prime95, and within a minute, the temperatures were back to 95-100 degrees C. The voltage reading was 1.16V.

The CPU cooler was cool to the touch under load, even the copper heat pipes right next to the CPU felt cool. All the brackets and mounting around the CPU seemed cool as well. The CPU heatspreader was warm, but I could hold my finger on it for a little while without it being too hot to touch (however after a little research it appears I may have touched the "cold" side of the heatspreader).

I built my computer about 18 months ago. Every few months I test the CPU temperatures at 60-65 degrees C at sustained 100% CPU load (most recent test was about 2 weeks ago). Nothing has changed in the past 2 weeks to the best of my knowledge. I dusted out the case (it was fairly clean) and tried to wiggle around the cooler (it was firm in place), with no change in temps.

Any ideas what could be up with this? I haven't taken the CPU cooler off and examined as I don't have any thermal paste to re-apply right now, and I'm skeptical that reseating the cooler would bring the temps down 40 degrees C, although it seems to be a possible cause since the cooler was cool even under load.

Specs:

CPU: Intel 6800K (Stock settings)

Cooler: Arctic Freezer i11

Motherboard: ASRock X99 Extreme4

Thanks in advance for any troubleshooting advice.

-Kyle

NelizMastr · December 1, 2017

When a CPU runs at those temps and you can't feel the heat on the heatsink, there's a problem with heat transfer. Repaste with decent quality compound. Also, that cooler is right on the edge for this CPU. It's rated for 150W and you're running a 140W CPU, which Arctic doesn't recommend, so that might be a factor too.

Bananasplit_00 · December 1, 2017

The thermal paste has lived out its life, time to replace it

KylePolansky · December 1, 2017

Thanks for the quick reply, I'll buy some new thermal paste this weekend and re-assemble everything to see if that fixes the issue.

As for the cooler, I'm re-using a medium-sized case and this was the best cooler I could find that wouldn't hit the side panel or interfere with RAM slots. It has seemed to work well other than just very recently, although a new case and cooler are definitely in store for my next build.