Dave Plowman (News) wrote:
I've got a home assembled PC based around an Asus motherboard. Which shuts
off at random. Not a controlled shut down - it just dies. Thinking PS
problems I've replaced it. Same thing. Sometimes it will boot up ok and
continue for as long as I want. Sometimes it switches off half way through
the boot sequence - but never at the same time. Any guesses? I've got AVG
free installed and that shuts it down after doing its tests. That sequence
always works ok.

Had that recently - oddly enough, seemed to be the graphics card.
Remove, reseat. Update drivers. Update firmware (on card and/or BIOS on
motherboard). Most complete fix was to switch graphics cards between two
identical machines - problem moved with the card but also became much
less frequent (once a month instead of several times a day).

Other things tried w8ithout success (but might be worth a go) included
checking memory using http://www.memtest86.com/, reseating memory,
patching Windows, setting graphics acceleration to minimal and all the
usual silly things that almost never help.

--
Rod