Hello again, same computer, new problem...

(A little precursor - dont think this is related but just for good measure... I just bought a UPS for my machine and had plugged my computer into it, turned it on, and it booted up fine. I let the scsi devices load and then reset it when it was about to load up windows because i wanted to change something in the bios i had been thinking about doing for a while (disabling hyperthreading. Then...)

Turned my computer on, it POSTs, but up to a point. I get the single beep, monitor comes on, the IWill logo, BIOS version and Press DEL to enter setup are displayed, along with Main Processor: Intel Xeon Processor 2.00GHZ, and then nothing. Usually it takes a few seconds, updates it to ", 2 CPU(s), then proceeds with memory check and drives etc. However now its just sitting at Main Processor: Intel Xeon Processor 2.00GHZ indefinately.

Thought at first it was somehow the UPS so i unplugged that, no go. Then thought it was the RAM but unfortunately its RDRAM and I don't have my placeholders so I cant pull out and test both pairs of sticks. Then tried pulling out processor #2, no go. Switched processors, no go. Put 'em both back in, no go. Pulled all my cards besides video, no go. Disconnected IDE, no go. So i'm thinking RAM, but cant test it, or motherboard, but it still boots up displays.

Any ideas?