Chosen Solution
My Mac Pro started acting weird, freezing up randomly but with long uptimes, then with increasingly shorter up times. Now won’t boot at all. Chime is also erratic. I pulled everything but the video card and keyboard. No video since it when down. At first the machine would start, no chime, optical would spin up, the main drive would spin-up, then stop, and then cycle again and repeat this cycle continuously. I checked all fans and they are working. However, on the last try I heard a fan that is weirdly changing speeds going from slow to fast, fast to slow.
Could I have a bad PSU?
I can’t believe this box is 11 years old. It has served me so well. I’ve got SSD PCIe cards, and an extra graphics card. I’d love to save this machine. She’s been so good to me.
Your diagnostic is correct. Your machine has a failing power supply. The main failures on this model have been #1 the video card, #2 the Power Supply. I have successfully repaired about a dozen and own one myself along with another 2009. Symptoms start when the machine spontaneously reboots. Over time the period shortens until it will not boot at all. After replacing the PSU I have not had one fail again. I do try to find new ones coming out of China as putting in a used one will result in the same failure. This machine is a real workhorse and is my repair bench machine. I am running El Captain on mine. Mac Pro First Generation Power Supply Unit Replacement
Sounds like the smc but check Louis Rossman’s youtube channel for confirmation as it will be covered on there.
Reverting to a known working GPU brought the video back to life. But the O/S was hosed up. So I had to reinstall and restore from a Time Machine back up.
