Monitor stop to work, Led monitor blinks

Dear friends,

I don't know if this problem is relevant to this section, but this is the closest one I can find to the issue.

Recently, I tried (not so successfully) to OC my CPU/Board. after It's didn't went so well I restarted my BIOS by jumpering and pulling out the battery and restored the parameters to their default.
From this day and on I cannot work for long time with my PC, after 1-2 hours my screen became black and the monitor LED starts to blink rapidly, the PC continues to work but no video signal is out. After restarting I can't even see the bios screen - so it can't be windows/drivers issue. and only after shutting down the computer and waiting for 2 hours I can work again.
I've two DVI outputs, one is connected to my monitor and the other to my TV. Sometime I can see work with my TV while my screen is dead. It's not a temp problem either (55C it's fine...).
I took my graphic card for a check in the store, but they say It;s OK (the run it on 3dmarks for over 16,000min.)

I don't know what to do and I'm quite desperate from this situation, any help will be more than appreciated.
my spec is detailed blow. sorry about the long story...
Thanks,
Amir


DualCore AMD Athlon 64 x2 4200+
KN9S
ASUS 4870
MaXtor 250GB
2048MB DDR2-800
ENERMAX Pro82+ 525W