Question: Power Supply Failure? Or Motherboard?
This morning I started to get a lot of problems with my Early Mac Pro 2008 (3,1). USB Ports and USB 3 PCI card stopped working, so I was forced to manually power down with the power button (long hold). Trying to power back up, when I press the button the fans are at jet engine speed for about 3-5 seconds, then the Mac then shuts itself off.
My reason to question whether this is the power supply or the motherboard is two things: 1) the failure of all USB ports & the PCI extension card (a USB 3 card - thought the SATA card I have in there and the built-in FW400 port seemed to working ok at the time the other ports were failing - I had drive plugged into both the SATA card & the FW400 port), and 2) the Mac did attempt to power on when I pressed the power button (if it were the power supply, wouldn't it simply fail to show the Mac any power at all?).
Before I buy a new power supply, I'm looking for experienced opinions about this. Questions? Ask away, please. Thank you!