My early 2008 2.8GHz 8-core Mac Pro died last week. I tried all the usual stuff and ended up taking it to the local Apple store genius bar. They ran their diagnostics tool on it and did not find any problems so I had to leave it for a more thorough test. The Apple Store called a few days later and said it was either the main logic board and/or one or both CPU's. They -say- they replaced the main logic board and that did not fix it. They told me it would be ~$2800 USD plus labor to replace the the main logic board and both CPU's. So I took the machine over to another authorized Apple Service center for a second opinion. This other service center seemed confident they could determine which component(s) are defective. I am expecting a call from them on Tuesday of this week and hope to find out more then. The symptoms are: When powering the machine I hear the startup sound and the display shows the apple logo. The machine boots for a little while (disk activity is heard) then the machine freezes for about 30 seconds then reboots or just freezes indefinitely. This happens with my 10.6.5 boot system, a second 10.6.x boot system on another internal drive as well as from the 10.6 SL DVD installer disc. Apple could not boot it off their network based systems either. Same symptoms on all startup disks tried so far... So, I'd like to know where to go if I need to obtain parts and do the repair myself. I've built a number of PC's in the past and have no concerns about the undertaking. I just need to determine which parts I need. I'm not looking to "upgrade" the machine however if faster CPU's are available for a similar price I'd probably opt for the upgrade. At this point I'd be completely satisfied replacing the defective components with the same stuff that's in the machine now. Any pointers/links/tips/etc. would be most appreciated.