Hi guys, I have been struggling to fix my Mac Pro 2,1 (8-core) Intel Xeon X5365 (Clovertown) processors (Early 2007) for many weeks now. I'm pretty sure that a logic board malfunctioning, but might be something else. Basically, when I press start up button, Mac turns on, fan on graphic card start spinning at full speed, start up chime and that's it. Black screens, graphic card fan spins at full speed, no any other sounds, no error chime, no light blinks, nothing. Could it be PSU issue? So, I'm planning now to replace logic board (661-4307) with one from Mac Pro 3,1 (661-4449) and keep the same CPUs and RAM? The reason is that I can not find the original board from 2,1. There are plenty 1,1 and 3,1 on sale and I think that 3,1 is a better option. I have read that 1,1 and 2,1 are compatible logic boards, but there is no information whether 3,1 is backwards compatible with 2,1 hardware and a box. Could you please advise if it is feasible to replace logic board as I described above? Would the logic board actually fit in? Is it possible to keep the same CPUs (Clovertown) and RAM (SMT 8 x 1GB PC2-5300 ECC DDR2-667)? Thank you!