I have a 2008 8-Core Mac Pro (3,1) When I got it, it worked fine. It was running off one internal SSD. I swapped the hard drives and after that, internal hard drives aren't recognized. I've tried multiple 2.5 and 3.5 drives. Nothing. White screen which eventually leads to the flashing ? folder. I tried connecting external hard drives and even internal an over eSata dock via USB. The Mac Pro reads them fine. I actually booted into my spare WD drive, which was my MacBooks former drive. It worked great. But still, no dice on internal drives. I've checked the connection to the logicboard, everything appears fine. Anyone have any suggestions or advice? Thanks!