Chosen Solution
I recently acquired a 2006 Mac Pro, which, according to the diagnostic LEDs on the logic board, has a fault on CPU B. I’ve tried replacing the thermal paste and checking all connections, but to no avail. I’ve also tried removing the second CPU entirely, but this still doesn’t work. The machine powers on and the fans spin up (the GPU fan in particular is rather loud), but nothing happens beyond that. It may also be worth noting that when both CPUs are installed, the system will push out a video signal, though it’s just a black screen. It appears to be restarting endlessly and encountering the same error. When only one CPU is installed no video signal is sent out. Am I missing something, or can the Mac Pro only boot with both CPUs installed (I’ve even tried putting the heatsink back and plugging in the temp sensor)?
One of my 2008 Pros shipped with only one CPU. I believe all the 2006-2008 Pros shipped with two sockets even when only one CPU was present. I did do an upgrade from a single to dual on my Mac Pro “Quad Core” 2.8 (2008). I’m just thinking out loud here. There was a fan syncing software program on the original system installation disk and it had to be used with any major tear down or you got run away fans. I would try booting from the original system installation disk. Let us know your results. Also that CPU should be dirt cheap. On my 2008 I went from a 2.8 GHz Q. Core Xeon E5462, to a 3.0 GHz Q. Core Xeon E5472 x2 for under $75 and most of that expense was the additional heat sink. Let us know what happens with the optical drive boot. You are going to have to have that original installation disk in any case. It can probably be found on eBay.
