GA-P55A-UD3 random shutdown and boot loop

[hal8000]

My PC has been stable for about 3 years:

GA-P55A-UD3   Bios F5
Intel i5 750
ATI HD5770    1G DDR3
Memory
Crucial Ballistix  2G  1333MHz 7-7-7-24   1.65V
Antec 650W PSU

Nothing is overclocked.
The system shut down after about 5 hours, After starting it powered on, 0.5 sec, off 0.5 sec and so on,
never reaching BIOS

I cleaned inside fan (only small amount of dust) and all seemed well for 5 days.
Now its happening again.

Luckily a friend built exact same system.
I am using me memory, graphics card and PSU on his motherboard and CPU.
All is working well.

Could this be a CPU fault or motherboard fault?
I have checked my Ga-P55A-UD3 with a magnifying class, no signs of electrolyte
or bulgings caps, (they are mostly solid state).
I hope the motherboard is ok, as they dont make it anymore, can always but a new
Intel

Thanks in advance for advice.
OS is Linux Mint 32bit, but do have a small windows 7 installation.

[hal8000]

Problem was the motherboard, I've found another on Ebay which I've ordered.

[hal8000]

After changing motherboard problem continued for 45 days.
Finally found fault, the humble front power switch.

If the switch contacts are sticking it can cause:
Your computer to switch on by itself
Your computer to switch off by itself
Boot loop, On/Off due to contact bounce
May not go through BIOS as if contacts touch, its set to instant power off

To fix:


Turn off the power, unplug from electric socket. If you can get access to front
case on/off switch blow compressed air over it to remove dust/debris.
Then operate on/off switch about 50 times fast to clean contacts.


The BIOS setting for power management is set to instant off on Intel boards.
If you have contact bounce or contacts are sticking or contaminated this will
cause this.

Post back if it solves your problem.
Hope this helps some of you.