One of my processors has gone AWOL. What used to be an 8-core 3.2GHz Early 2008 Mac Pro now shows up in System profiler as a single processor Quad-Core Intel Xeon. I have been unable to find a way to run the Apple Hardware Test (AHT) on my machine. I can't find the OSX Install DVD. Starting up with Option-D doesn't work... I have considered taking apart the Mac and trying to reseat the faulty processor - as outlined here: https://www.ifixit.com/Guide/Replacing-Upgrading+Mac+Pro+Processors+(Early+2008)/17562 but I don't have the thermal grease. The timing of this couldn't be worse: I have just ordered 16GB RAM to bump my old Mac up to 32GB. I have also ordered the Seritek 6G2+2 PCIe eSATA III card and two Samsung Evo 850 Pro 1TB drives. They arrive tomorrow. I have no idea what happened to the processor - the last thing I did was move my existing Apogee Symphony 64 card from slot 2 to slot 3 to prepare for the Seritek card. It was only when I was running Logic Pro X and I brought up the CPU monitor that I realized I was only using 4 threads. I'm at my wits end here - am hoping that one of you Mac gurus may be able to suggest something I could do to resuscitate my wayward processor. (In my heart, I don't believe that it has failed. Wishful thinking, perhaps.) I am in South Africa - there is no easy access to reliable repair specialists. Or replacement parts. I literally just made the decision to try and squeeze some more life out of my MP3,1 as opposed to buying a new McDustbin and figuring out a way to use my PCI cards with a Thunderbolt enclosure... In effect, I feel like I just blew $2000 on new mag wheels for a car that was stolen while they were being delivered. Any suggestions? (Please be gentle!) Thanks.