CPU Temperature sensor failure?

Steviepunk

Steviepunk

Steviepunk

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11 Mar 2008
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I'm running an AMD 5900X, Gigabyte X570 AORUS ULTRA motherboard and a be quiet! Silent Loop 2 360 High Performance CPU Water Cooler

Over the weekend I noticed that the CPU cooler fans were spinning up frequently and getting quite noisy while sitting on the desktop (with just Chrome and Firefox open but minimised), not something it had been doing before.
In this fairly idle state, CPU temp was going going up and down a lot, moving between ~65c and up to ~80c (even the odd spike to 90c at one point). During this, CPU utilisation was around 5 to 10%, however 1 core was often around 100% utilisation. I tracked that usage to a Microsoft search process and killed it, however even at virtually no CPU utilisation the temps were still going up to the ~75c regularly.

Even when the CPU was showing 90c temps, the air coming out of the radiator was still cold (not even warm)

Based on what is happening, my guess is that it could be one of two issues:

AIO cooler pump is not pumping correctly, therefore not removing heat effectively (I checked the 'fan speed' for the pump via Open Hardware Monitor the rate looked normal, though can't remember off the top of my head what it was... ~2500rpnm maybe?)

or

The CPU temperature sensor is not correct, resulting the fan curve kicking in when it's not really needed.

Based on the air being cold coming out of the AIO radiator and the fact that other temp readings (Core Average and CPU package) were barely over 60c when main temp sensor was reporting 75c, I'm leaning towards the issue being the sensor, even though I'd would expect that the the likelyhood of the AIO pump failing is probably much more likely than a temp sensor failure.

Does anyone have any experience of this behaviour, or any suggestions of other things to check?
 
I seem to have resolved the problem.
I checked the radiator and it was full, no need for any top up. However, I did find that on the pump block on the CPU I was able to tighten the screws by around a 1/4 to 1/2 turn on each of them. Not sure if it had always been that way or had vibrated loose over time, however on restarting temperatures remained much lower. Over a 5 hour period, 4 of which were gaming, it hit a peak temp of ~70c
 
I'm guessing my fan settings on the MB have reset themselves now (tho BIOS settings look normal)... fans were going crazy again, spinning up to 100% speed again, however this time the CPU temps are normal. When I start up fan control things return to normal speeds/noise (and temps remain normal), so manageable but very annoying during start up!
 
Well, the CPU temps didn't stay normal for long, started having issues again a few days later. I decided to remove the pump/block, clean it up and put on new paste and this seemed to work... until yesterday when idle temperatures jumped back up to the 70 to 70c range (90+ during gaming).

Having been through the other steps I'm starting to think that it's the pump that's failing on the AIO... even though it's speed seem consistent and normal in the system sensors.

Is there anything else I should check before I buy a new AIO?
 
Is the mount using the standard AM5 socket mount or is it screwed directly into the backplate? If it's the former, it's worth checking the screws are snug on the plastic shroud.
 
Into the backplate (connects through the PCB). I was careful when reapplying the paste to make sure it was screwed back in tightly (but not too tight!), had seemed to be good for a week before issues started again
 
Steviepunk said:
Into the backplate (connects through the PCB). I was careful when reapplying the paste to make sure it was screwed back in tightly (but not too tight!), had seemed to be good for a week before issues started again
Click to expand...
The AIO mounting system should prevent you from overtightening the cooler. It could be that your perception of tight isn't providing sufficient clamping force. The coolers generally bottom out at the correct mounting pressure.
 
As above.. You sure it's actually tight enough?
They need to be nipped up pretty tight, but not Arnold Schwarzenegger tight to the point your bending PCBs and grinding screws up.

Also that chip is what about 150w balls out worst case scenario?
You could just whack a thermalright tower cooler on it for not much money.
 
I rechecked the screws again yesterday and it definitely would need major effort to turn any further (they did get an extra quarter turn or so on Wednesday evening).

I've changed some of the fan header for the pump to rule that out, still has the same readings. Yesterday the temps were up to 40/50c just sitting at the BIOS, then on the initial desktop and minimal CPU utilisation it was up to around 70c. For now I've resorted to underclocking to keep a stable temp.

I think I'll have to replace the cooler. I know the Thermalright coolers are well regarded, but I do like the AIO units - I suspect I'll go for the Arctic Freezer III as it seems to have very good reviews.
 
I didn't notice anything unusual about the mounting, the cooler or the board.
I'm certainly thinking that it's the cooler that is the problem. It had been working fine for several years, then suddenly temps start spiking. Although I though I fixed it a few times, I think the common factor to each 'fix' was that the computer had been on it's side while I worked on it, then put back to normal when I'm done - wondering if the orientation change was enough for the cooler for start working again for a while, then it gets back to it's problem state in about a week.
 
Steviepunk said:
I didn't notice anything unusual about the mounting, the cooler or the board.
I'm certainly thinking that it's the cooler that is the problem. It had been working fine for several years, then suddenly temps start spiking. Although I though I fixed it a few times, I think the common factor to each 'fix' was that the computer had been on it's side while I worked on it, then put back to normal when I'm done - wondering if the orientation change was enough for the cooler for start working again for a while, then it gets back to it's problem state in about a week.
Click to expand...
Sounds like there's air in it - it's probably dead and time to replace.
 
Fitted the Arctic Freezer III at the weekend, immediate difference in temps. At in the underclocked state (a still usable 3.8GHz) at idle, temps dropped from 55-60c down to 30c. At normal clocks, temps had been around 80c at idle, now down to 45-50c.

Hopefully it stays this way this time. On the down side, there is a hum coming from the PC now that wasn't there before, which I think is the VRM fan on the cooler... unfortunately it's not responding to having a fan curve applied (yet at least, haven't had time to look into it)
 
You can always unplug the fan if it can't be controlled and the VRM temps are fine without it.

Good news on the new cooler front though. I'm sure it'll be fine!
 
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