GA-Z68AP-D3 rev 2.0 cyclic boot problem

[Rdop]

Hello,

Problem:
Yesterday, I started my computer after three weeks idle(not plugged in).  Everything seemed perfectly fine.  Updated windows and upon restart received a message about overclock voltages.  Since then the system will only boot to splash screen and then shut off, only to restart again after a few seconds.  I get the normal single beep, all LEDs on the mobo stay illuminated.  Occasionally I can pull up the POST screen, but then system shuts off.  Cannot get BIOS or Qflash to come up at all. 

What I've tried:
Unplugged PSU, held down power on switch to drain capacitors.  Cleared CMOS according to manual, also pulled battery for hours.  Removed one stick of RAM, tried different slots, sticks.  Removed sata drives, graphics card.  Still no change.

System specs:
i5 2500K oc'd with Easytune6 to 4.01 - watercooled with corsair CWCH60, GA-Z68AP-D3 rev 2.0 FD bios, corsair vengance 8gb, corsair 750W psu, EVGA GTX580 3gb, 1tb WD hdd

Any help or ideas are greatly appreciated as I am missing my first gaming build immensely.  From what I've read so far I'm guessing this may be a RMA back to gigabyte

thanks again

[Rdop]

Also tried bread boarding the mobo today after having the CMOS battery out all night.  Tried all different combinations of tests as above, but still get the continuous boot loop.  Any ideas?  Or should I just RMA?  Thanks.