My system has just restarted from its second switch off today. I was happily playing GTA:Vice City when the system suddenly powered off without warning. It did the exact same thing earlier when I was about to plug my digital camera in.
The system wont switch on again till I unplug it at the wall and plug it back in again.
Looked in system log and there was no error messages. Device manager gives it the all clear and my CPU temperature is about 50-55'C.
I just moved everyhting into a new case last thursday and everything has been fine since then.
My power supply is desinged to run for a few minutes when the system is powered off so that the fans cool everything down. When the system shuts off the power supply fans continue running like they do when you shut the system down. There is no warning that the system will shut off...it just goes off like someone has pulled the power out.
I have another system on the same power strip and that one stays on ok.
it just died and I unplugged it all, plugged it back in and it died about a microsecond after boot. everything now unplugged (fans and neons + other rubbish) except the CD, the Hard disks, the CPU fan's molex and the motherboard. Booted OK but died when it got to Windows Ctrl + Alt + Del dialog and i was typing my password.