Desktop computer just shuts off

My desktop computer shuts down without warning. I could be on the internet, listening to music, whatever and totally off. I've updated all drivers, made sure the inside is clean (only one year old with 6 fans), reloaded Windows 7 Home Premium, ran temperature test/monitor software (not hot at all), ran ram tests, ran cpu tests all seem OK. I have an AMD Athlon II 640 processor 3.00 GHz, 4.00 GB RAM on Windows 7 64-bit and I'm at my wit's end.

 

It even shuts down in safe mode....I was only running an AVG scan and it shut off about half way thru it.

 

have you checked for malware/viruses?

 

Tried a different outlet or power coord to the unit? thats the first easy setup in trouble shooting that.

 

Does sound like a power supply issue. Hopefully it's just the cord. Try pulling the cord out of the back of the power supply and re-inserting it a few times. Make sure it fits all the way in. I've had some cords that had to be pushed in very firmly to make sure they were all the way into the socket.



Now, for some reason, I feel like I need a cigarette. :confused

 

I have ran AVG, Spybot and Norton a bunch of times....I've tried different surge protectors, different wall outlets, and differnt rooms. I have unplugged all cords a few times, but have not tried a totally different cord altogether (I'll give it a try)....for the first about 10 months no issues though.
I'm going to BestBuy this morning to get some thermal compound for the heat sink...giving this a shot too. Thanks for all the replies and keep them coming, I'll let you know about theses two tries.

 

Possibly needs to have the thermal paste refreshed.
Sounds like an automatic shutdown to save the CPU.

 

Well, I redid the thermal paste and tried a new power cord on Saturday morning and so far so good...thanks all:-D

 

Hopefully resolved.