GA8iK1100 rev2, second mobo dead

Hi,
I just can't understand how 2 mobos can die in so short time:
I pepared a computer for a family member for Chritmass and based it on a
8iK1100 mobo, with a p4 2.6C and 2*512 of PQI mem, every thing was OK at
3.200 Mhz I didn't install the OS after 3 weeks the mobo burned. Seem to be
too many reboots!
I got back the entire computer and installed a new 8iK1100 mobo, but this
time I installed XP and made a few Ghost Image, this was in January, up to
now everything was perfect. Not even a reboot.
But today I had a call, (computer is 800km away) the mobo seems to be dead
again.
While stopping the computer hanged, so he pushed the buttom for 4 seconds
and no way to start again.
I'm afraid that if I change again the mobo for the same gigabyte I will get
the same call in a few months.

What can be the problem with this computer?
motherboard's capacitors are too just for overclocking, or graphic card
taking too much power supply.