I'm attempting to troubleshoot or at the very least identify the issue with a Mac Pro a former employee sold to my employer. I've run down all of the obvious suspects. Did NVRAM/PRAM reset, booted in recovery mode, swapped three different drives (SSD and HD) and nothing. The computer boots to a blank, white screen. I do want to note that it does recognize the drives only when plugged in USB via eSATA connector. I have come to the conclusion that it's either the internal SATA cables or the logic/motherboard going bye-bye. Is there something I'm overlooking, is it perhaps something a little less crippling than a screwed motherboard? I'm just trying to see if there's anything else I can do before heading to the Apple store to be told I need to pay the heinous price tag for a nice board. Any help would be stellar!