You still might be drawing too much off the 12V line. It is the most common problem with random reboots. Have a look at the users manual, I think the limit on the 12V line is 6.5A peak. I had to underclock my athlon XP1600+ so that it wouldn't reboot by itself. Do you have a 2.5" Laptop drive or usb drive you could try? The reason for this is that they only use 5V.