Old AMD CPU overheating strangely

[spiderwheels]

I'm doing a favour for my friends. Their PC restarts at random times. I suspected overheating and put speedfan on and CPU temps are 60c-75c. I checked it in the BIOS too and it was about the same.

It is an AMD Athlon64 X2 5400+.

It has a weedy looking Akasa heatsink that I cleaned up and refitted (there was far too much thermal paste on it) but it hasn't helped.

What is strange is that running it under load (prime95) the temperature rises slowly from 60c-70c and then drops back to 60c again before rising slowly once more. It repeats these cycles and gradually starts to rise (say 61-71, 62-72 etc).

Also strange is that sometimes it will play games for hours and sometimes it will restart almost immediately after booting with no load which doesn't hold with the overheating theory.

I have read that these CPUs can have inaccurate temperature sensors which could mean the reading is off by 10c but that doesn't explain how it can cycle up and down so much under load.

Unfortunately my friends don't have a lot of money and can't afford for me to start replacing components otherwise I'd replace the CPU with whatever else the motherboard can handle just to rule it out.

Any suggestions?

Thanks

 

[frozentundra123456]

I'm doing a favour for my friends. Their PC restarts at random times. I suspected overheating and put speedfan on and CPU temps are 60c-75c. I checked it in the BIOS too and it was about the same.

It is an AMD Athlon64 X2 5400+.

It has a weedy looking Akasa heatsink that I cleaned up and refitted (there was far too much thermal paste on it) but it hasn't helped.

What is strange is that running it under load (prime95) the temperature rises slowly from 60c-70c and then drops back to 60c again before rising slowly once more. It repeats these cycles and gradually starts to rise (say 61-71, 62-72 etc).

Also strange is that sometimes it will play games for hours and sometimes it will restart almost immediately after booting with no load which doesn't hold with the overheating theory.

I have read that these CPUs can have inaccurate temperature sensors which could mean the reading is off by 10c but that doesn't explain how it can cycle up and down so much under load.

Unfortunately my friends don't have a lot of money and can't afford for me to start replacing components otherwise I'd replace the CPU with whatever else the motherboard can handle just to rule it out.

Any suggestions?

Thanks

I would check the power supply. I had similar symptoms, and finally noted that when it was having the problem, the power supply fan was stuck and not spinning. Apparently this was causing the power supply to overheat. Or the power supply could be just getting old and is defective.

 

[AnonymouseUser]

Very well could be the PSU, but check the CPU fan and make sure it works correctly. It shouldn't struggle to start, and as the CPU heats up it should gradually spin faster. You can also check your monitoring software to make sure it's spinning at the correct RPM for the fan.

 

[spiderwheels]

The fan is fine. The heatsink is seated correctly.

It is the see-sawing CPU temperature that has me stumped. It should just keep getting hotter under continuous load and not jump down again.

 

[Plimogz]

If Prime is set to blend, the mix of different FFT sizes will result in varying max temperatures under load.

Given what you've reported, RAM and PSU are likely culprits.

 

[unhuman]

Could be the BIOS. One of my motherboards (Abit, maybe) needed a BIOS update to fix improperly reported temperatures. I think it still wigs out.

 

[spiderwheels]

Thanks for the suggestions.

I ran MemTest to check the Ram but it kept shutting off after a few minutes. Booting in the BIOS showed the CPU temp at over 70c so I just sat and watched it in the BIOS hardware monitor. As soon as it hit 78c it shutdown.

I repeated that several times and it was predictable, shutting down at 78c everytime.

A BIOS update didn't fix it.

The heatsink is an akasa ak-865 which, while quite small, is rated up to 89W TDP and the CPU is rated at 65W TDP so it ought to be OK.

Assuming it's seated properly (I've re-seated it with no improvement - and I've fitted several heatsinks in the past with no issues) why would the CPU still overheat?

 

[AnonymouseUser]

Assuming it's seated properly (I've re-seated it with no improvement - and I've fitted several heatsinks in the past with no issues) why would the CPU still overheat?

You either didn't use any thermal paste, or the heatsink is not seated properly.

 

[spiderwheels]

I bought another identical CPU off ebay and that doesn't have the problem. All fixed now.