I can't get the machine to boot with the 4pin plugged in. It just turns on for half a second then off again, It repeats this many times. If I unplug the 4 pin 12v connector it stays on but no display.I had a Asrock P4VM800 motherboard and a Celeron D 2.66 without any overclock or heat problem in the past. Last week when I turn it on for about 5-10 minutes, it shut down automatically and never turn it on again. My first thought was my power supply (not even fan turning), but after I changed one, it is still dead, leaves only a power light at the front panel, this time I'm sure is not power supply, definitely cpu or motherboard. When I unplug the 4 pin ATX12V power, everything seems back on (Hdd, power supply, cpu fan..) but of course without plug in the ATX12V, it can't be working. Is this motherboard fail or cpu?