Recently I changed the Zalman 9500 fan to a (larger) Zalman 9700 fan. I had to remove the motherboard to get access to fan, so I photographed connections to mobo and put them back the way the were, as far as I can tell. For heat sink, I used Arctic Silver Ceramiqué sparingly - enough to get a reasonably even thin white coat - spread with plastic bag on finger per instructions. Yes, I cleaned off the old material first with isopropyl 70%.

The system runs fine for 2-3 hours, then the screen goes blank, and the system powers off. Restarting it results in a blank screen, or a partial boot then hang at various points, sometimes a full boot. After is sat overnight turned off, it had the same behavior this morning (works fine for a couple hours, then crashes). Ambient temperature is 68-75F.

No messages to clue me in. My instincts say this is a thermal problem (especially since I just changed the fan). I have no idea why. The pipes on the 9700 fan are quite cool to the touch (shouldn't they be warm or hot?). The fan runs fine. I followed the instructions for Arctic Ceramiqué.

Nothing else in the system seems particularly hot, except a hard drive that was being formatted.

It could also be related to the hard drive... I was copying 400GB of files from one drive to another when it shut down yesterday; I was formatting a 750GB drive today when it shut down. I thought I saw a blue screen about a hard drive briefly yesterday.

BTW hard drive configuration: 2 x 72GB 10k rpm, 1 x 750GB 7200, 1 x 500 GB 7200, all SATA.

Any help in getting this system stable will be most appreciated.

Tuck Runo