A friend has an early 2008 Mac Pro 3,1 and the fans occasionally spin up to 100% and it locks up. I am trying to find out what is wrong with it. I reset the PRAM and afterward I could not repeat the fan issue. All diagnostic lights on the logic board look good. I ran the Apple Hardware Test on it and it passed the short test, but on the long test it detected the error 4SNS/1/40000000: TH0P-128.000
That code indicates a hard disk temperature sensor failure in hard drive bay 1. This Ambient Board is Apple # 922-8524, mfr # 820-2203-A (which I can also see embossed on the part). I purchased a replacement on eBay, but the seller sent me Apple part # 922-7732, mfr # 820-1974-A, which is for the 2006/2007 Mac Pro. The seller tells me it's the same part, but I don't want to put in an incompatible part. Does anyone know if these Ambient Boards (2006/2007 and 2008) are interchangeable?