i7 CPU Thermometer breaking down?

I have a custom build with a Intel Core i7-3820 on MSI X79A-GD45(8D) X79 motherboard.

I'm using Thermaltake CLW0215 Water 2.0 Performer as CPU cooling.

I have this build for about a year now. Back then, when starting my PC, the CPU temperature at idle would be around 27-30C and would never go over 60-65C under heavy load.

However, this week when starting my PC, it showed 55-60C on startup and could peak at 100C under heavy load. It looks like it's totally unable to go under 55C now, even if nothing is running at all. Using Power 95, I noticed the temperature rise very quickly, but also drop sharply when the test stops. Does that mean the cooling still works?

Dusted it off all. All fans spinning... Can't be really sure if the water pump is working, as it never made any sounds to begin with. But I would guess if the pump never worked, I wouldn't have stayed at 30C... I would be at 100+.

Does the CPU thermometer can be stuck at +30C than normal? Is it even possible for a CPU thermometer to be messed up? What should I be doing to see if there's an error or if there's a material issue?

LightStriker

Posted 2013-11-17T16:45:13.623

Reputation: 103

Yup. Dusted it off all. All fans spinning... Can't be really sure if the water pump is working, as it never made any sounds to begin with. But I would guess if the pump never worked, I wouldn't have stayed at 30C... I would be at 100+. – LightStriker – 2013-11-17T16:58:12.260

Answers

Assuming that the cooling system itself (fans, pumps, etc.) is running normally, this sounds to me like insufficient heat transfer from the actual CPU die to the surrounding air.

The most common way that could happen is if the thermal paste evaporates for any reason, and that can happen if the CPU temperature gets much too high at some point. It could also have been displaced, if the system has been exposed to physical stress.

I would apply new thermal paste first, and see if that helps. It's cheap, and it's likely to solve the problem.

a CVn

Posted 2013-11-17T16:45:13.623

Reputation: 26 553

Already ordered some. I'll cross my fingers that it's that simple. – LightStriker – 2013-11-17T16:55:39.437

For some reason, the "stock" thermal paste that came with my cooler did some bubbles and half of it was most likely evaporated. It now stays at a steady 45-50C and <75 under load. It's not as good as when I first build this computer, but at least now it won't burn itself out. – LightStriker – 2013-12-08T18:55:16.163

@LightStriker Glad to hear it helped. – a CVn – 2013-12-08T22:09:52.390

Use RealTemp. Only reliable way to get readings (for Core series).
About the cooler... well if you don't overheat during a load, it sure works.
Even on idle the temps would go through the roof in minutes.

But you can:
1) Clean off dust from cooler. If you have a can of air, hold the fan so it does not spins up as you blow air on it. (That could kill the fan.)
2) If you have any PC shop around, or an experienced friend, get the thermal paste changed.

The sudden drop-raise is not a failure, it's just that's how it works.
Once you start something demanding, sensors will kick up ~ +10-15C to the temp.
When the load goes off, they drop by that much again. RealTemp won't do this though. It always shows the real temperature in cores.

Oh, and never forget about ambient temp.

Apache

Posted 2013-11-17T16:45:13.623

Reputation: 14 755

Temperature I'm saying here is while using RealTemp. How can the CPU be at 60C while there's nothing at all going on? (Ambient temp is 23C) Also, RealTemp got to get its data from somewhere... Can that be off? – LightStriker – 2013-11-17T16:52:31.123

With all that said, the cooler can fail. But I haven't seen a "slow" cooler, only totally dead ones. – Apache – 2013-11-17T16:53:28.553

I did already do the "dust" cleaning. There wasn't much dust to begin with and it didn't change anything. I ordered some thermal paste off internet and I'll see if that changes anything. But from what I understand, the thermometer in a CPU can't really break? – LightStriker – 2013-11-17T16:55:00.153

It can't. It can be dead by default (my friend's AMD is on - 0-45C all the time.) Talk about freezing temperatures. Speedfan may also help. Check the RPM of the fan if you can see it. And check what the RPM should be. – Apache – 2013-11-17T16:57:23.583

Oh haha. You are using a water cooler. How did I skip that... pfah. Sorry. If so, try re-applying your cooler. Maybe it went loose somewhere so it does not contact the CPU that closely. Maybe... worth a shot. – Apache – 2013-11-17T16:58:14.807

Will do once I get that thermal paste. – LightStriker – 2013-11-17T16:59:58.690

Alright. Good luck. – Apache – 2013-11-17T17:01:24.083