I have an early 2009 Mac Pro Tower that has 5.1 firmware and upgraded chips.
My issue is that if keeps randomly shutting down then wont boot back up for some time. This has been getting gradually worse over time.
At this stage I can hardly even get it to boot up at all as it will stall at various stages.
I can conform that the problem isn't with the Power Supply or Ram nor Hard Drive as all have been tested or replaced with no change in condition.
Thanks in advance for your help.
[Re-Titled by Moderator]