[UPDATE] Unsure as to the cause of this problem
So last week my PC unexpectedly shut down for no apparent reason, and all efforts to make it start again failed. I believed the problem lay in the motherboard as the PSU was still apparently working fine; when switching the PSU on, power would flash through the system and then die completely. However, when I installed the new motherboard (exactly the same model as before) the problem persisted. After plugging in the power cables again, one at a time, the system booted up, but then crashed after a few seconds, restarted itself, crashed, and repeated that cycle until it would just hang, power on, but before the POST test. Since then, I removed the power and cables for the secondary HDD, SDD and optical drive (the boot drive is a RevoDrive), but that didn't change anything.
Now I'm thoroughly stumped, and I'd appreciate any advice that could point me in the right direction.
ASUS P6X58D-E -- Intel i7 930 @ 2.3 GHz -- NVIDIA GTX 570 -- 6x2GB OCZ 1.5GHz -- Corsair 1200W PSU -- RevoDrive 50GB (Win7 64bit Ultimate) / Crucial 64GB SSD / Samsung 7,200 RPM 1.5TB -- Antec 900