Hello,
I have a round about 5 year old GA-P55M-UD2 Motherboard with:
I5 2.6 Ghz
Ati HD 4890
A week ago, about 5 minutes after i started my PC it simply goed off, without a Bluescreen or something like that.
I was not able to reboot the PC and tried it about 24 H later. The Pc worked then for 30 Minutes and was simply going off an 2nd time. After that i was not able to boot, never mind how long i waited.
So at first i exchanged the power supply unit, but this didnt changed anything.
I checked every Ram-Modul and even the CPU, everything looks fine.
It was just so, that when pressing the Power on button, the Motherboard Led´s will led up for 2 seconds and are going off after that, the fans will circuit for that short time.
So at the end i found out, that i can boot up the pc when i do an CMOS Short-circuit, exactly in that moment when the Motherboard LEDS are led up.
I exchanged the Bios Battery, but even that does not fixed the problem.
I have to say, that i overclocked the pc from Bclk 133 to 166, so that i had 3.34 Ghz instead of 2.6 Ghz.
But that was stable for about 5 Years.
I would be very thankful for every help.
