I am having this problem since i installed my new Mobo.
I have checked all the fans and they are clean and working fine as is the heatsink for the CPU. i also reapplied thermal paste to the heatsink.
As this is a new Mobo i haven't been able to install windows but i found out the CPU was overheating as the PC kept shutting down and i accessed the BIOS and checked the CPU's temp it went all the way up to 90. C
The PSU i have has 750w of power and the CPU is an AMD 64 x2 Ahtlon Socket 939

Can anyone help please
ThanksDouble check the heatsink and thermal paste, also make sure the fans are working.Paste application might be the problem if too much is applied....follow these guidelines and see if you applied it OK.

http://www.arcticsilver.com/pdf/appinstruct/as5/ins_as5_amd_dual_wcap.pdfdone all those and STILL it overheats
Can the CPU be damaged in anyway even if i can access the BIOS ?
Ive had exactly the same problem with exactly the same components. The only way i got it to work was to buy a heatsink for a quadcore. Then when you put the new one in, with the thermal paste, leave over night before you turn it on. I also installed SpeedFan and turned up the RPM to about 55%. It works fine now!! But I had loads of trouble before I found this solution. Nothing seemed to work and I thought it was the cpu.hmm thx Reddevil
The problem for me obviously is to discover the source of the problem
i do not wish to buy unneccesary items
Well, the problem is overheating. I'm sure that thats the only way to keep the heat down. The heatsink I bought wasn't EXPENSIVE, maybe £25. I think there is no other way to solve this. Thanks i'll try that
The only reason I say that is because, like I said earlier, I had exactly the same problem. I was upgrade from an Athlon 64 to a Athlon 64 x2 and my mobo has Socket 939. I have a 750 watt PSU. I didn't even give me time to do anything except check the BIOS before it shut down. I tried everything I know of and posted on several forums, but to no avail. That is the only thing that worked for me
Hope it works for you too.

Good Luck.

RDgggBought new heatsink and fan and now the BIOS page will not LOAD so i cannot check at what temp the CPU is running with the new heatsink.
I end up with flashing cursor at the top LEFT on a blank screen
Faulty PSU?
Double check the memory is seated, in fact remove it and reseat it, then swap in a known good powersupply, check the video cards seating as well....check all connections too.Good on you Karnac...I watch, I listen, I learn.........Thanks Patio.