Advanced Micro Devices Inc (AMD)

[Not a Short]

The cleaning of dust is a good idea, your motherboard/video card/etc aren't going to have fan/temp sensors in every possible spot so you aren't likely to know what component is overheating.

Once you have cleaned the dust out you need to look for bad capacitors. Look at www.badcaps.net for examples. A swolen or leaky capacitor could easily explain that behaviour. If you do have bad caps the easy answer is to buy a new motherboard if you are a do it yourself kind of guy or buy a new PC if you aren't.

If it isn't dust or badcaps then you get into the messy stuff:

If you are overclocking it move the settings to be less agressive. If you aren't overclocking the symptoms are similar to overclocking with issues ranging from:

PSU supplying voltages out of spec.
BIOS/Jumper CPU voltage set too high
BIOS/Jumper CPU voltage set too low
BIOS/Jumber FSB speed too high
RAM delay too low (low equals fast)

there are a lot of settings that could be off and affect stability.

The not so fun of all of this is that the part requests a voltage, the BIOS can overide that request, and the PSU can mishandle the request.

You can try experimenting with values in the BIOS or you can pick up a mulitmeter and do the dirty work of making sure the voltages are correct. Myself I don't use a multimeter for anything but testing a battery.