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PC Powering Down Randomly, CPU related

Last response: in Systems
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July 20, 2010 8:53:28 PM

Hey people,

My system is a home-built gaming machine and has lasted me two months in its current configuration (I upgrade fairly regularly). I have had the machine for 3 years though at this point it has none of its original parts.

Two months ago I fitted an E8400 3gz core 2 duo processor and it seemed to work fine but now the machine powers off after being on for a while. My motherboard usually only clocks the CPU at what is needed so it normally sits at 2.2ghz but now it constantly sits at 3.0 (I use the LCARS gadget to monitor this).

The PC can be on for a few hours and run fine under low stress but it will always shut down eventually. If I do anything demanding (like video editing or rar extraction) it shuts down within 15 -30 minutes.

The day before this happened I did a batch conversion of about 15 720 videos and the machine handled it fine (I don't do this very often).

There is no BSOD, or warning, the machine just instantly cuts dead regardless of what its doing, the only error logs I can find are to do with recovering from unexpected shutdown and have nothing to do with the cause of the problem.

I left the PC running the next day with CPU temperature Monitoring software and after 1 hour the temp was normal but the app had logged the highest temp reached in the 90 degree area!

My spec is as below:

Case: Cool Master Cosmos S
CPU: Intel E8400 Core 2 Duo 3.0GHZ
GPU: XFX 8800GT 512mb
PSU: Thermaltake Toughpower 700W
CPU Fan: AKASA AK925 REVO THERMODYNAMIC
Memory: Geil PC2 6400 2gb with heat sink X 2
Motherboard: ASUS p5n-d
OS: Windows 7 Ultimate x64

also I have a small pci soundblaster sound card and a pci usb card.

I'm running at a resolution of 1680x1050 and play games on it all the time.


The case is on my desk and its air vents are totally unobstructed.

I am really at a loss here, I don't know where the problem is but I think its to do with the cpu and the temperature.

Can anybody help, I'd really appreciate it.

a b B Homebuilt system
a b à CPUs
July 21, 2010 2:02:48 AM

It sounds like the safety shutdown on the CPU temp. Check your shutdown temp in the BIOS, my default for core2 CPUs is 85C; I changed it to 75C.

If you are happy with your current setting, then check the fins on your HSF to make sure they are not clogged with dust. If that is OK, you could re-set the HSF, clean off the old TIM, replace it with fresh TIM, and make sure the HSF is properly seated onto the CPU and the board.

a c 122 B Homebuilt system
a c 172 à CPUs
July 21, 2010 1:53:54 PM

youngwolf0 said:

I left the PC running the next day with CPU temperature Monitoring software and after 1 hour the temp was normal but the app had logged the highest temp reached in the 90 degree area!

90 F is OK. 90 C is much too hot.
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July 21, 2010 8:19:38 PM

It was Celsius... I just tried leaving the machine running in bios to see what happned and the mobo temp gauge showed it at 105 degrees c and climbing! I shut down the PC and touched the heatsink which was cold. But when I touched the contact point between cooler and cpu it was hot enough to burn me.

Is re-seating the cooler and paste enough? if not has anyone got any thoughts on a good replacement cooler? This is the first time I have not used a stock cooler and I perhaps didn't make the best choice. I'm not sure the liquid coolant is flowing properly anymore.

I am happy spending up to £70 on it online and I live in the UK, any input would be appreciated.
!