In article <JE_bc.181877$_w.1839554@attbi_s53>, Tony Payne says...

The cpu is frequently overheating, very often at the end of 1 WU and the
start of another.  I have checked the cpu and fan mounting, have the right
amount of thermal compound etc etc, but it's really frustrating to find your
system powering itself off every couple of hours.  I also don't want to fry
the processor or motherboard.

Change your fan.
Even some extremely cheap fans will do the job properly.
I have a XP1700+ overclocked to XP2200+ rating (1800mhz) and it runs around 
45�C under full load (seti).

Even during hot summer days it never goes over 55�C.
The fan is GlacialTech Igloo 2400PRO which was around $10 year ago, and is
one of their lower end fans.

So look into it before your CPU dies. 

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