Crap aint it, its probably sometime simple. I have recently built a new system and encountered numerous problems where it would boot, then not.
I would try disconnecting the c-cell battery and leave it out for 30mins or so.
It is stopping at the memory stage, is it counting the ram? or gets stuck prior to this?
Try loading optimal defaults in BIOS, it seems that your pc is finding a fault when booting ie a dodgy hardware issue.
Within BIOS on my Mobo, there is a issue to disable "Halt on Errors." make sure this is disabled and save and reboot.
If the PC is turning on I would say your mobo is fine.
hope this helps