Mac Pro Issues won't start, need help please

[chefs chocolate salty ...]

Hi All,

I want to start and say I'm not familiar with troubleshooting macs all that well but am familiar with computers in general. My friend has a mac pro (I have one too) and he said it wouldn't turn on and sometimes it would and he would use it and it would just shut off randomly. he also wanted to upgrade the GPU and add in a 3rd hard drive. So he brought it to me i plugged it in and it worked fine. turned on no issues. I upgraded him to an RX480 GPU, did the trick in sierra to allow for a Polaris GPU to work, added and formatted a 6TB hard drive for him. tested everything and everything worked great. no issues. Only thing was the GPU has a connection to add 2 power plugs in it. I only had 1 at the time but it was still working fine. I ordered a 2nd one, plugged it in and gave it back to him. Then all of a sudden it went back to the same issues i never seen on it of not starting up. it doesn't do anything. If you press the power button I just get a click noise and then nothing. Any ideas what it could be?

Quick edit: Mac Pro early 2009, Dual xeon CPUs, 32Gb RAM. OS Sierra

 

[thats all folks]

does he use a UPS? maybe that's gone bad. a faulty power strip? a dying or overloaded circuit breaker?

try changing everything related to power delivery to the machine and see what happens then.

 

[chefs chocolate salty ...]

does he use a UPS? maybe that's gone bad. a faulty power strip? a dying or overloaded circuit breaker?

try changing everything related to power delivery to the machine and see what happens then.

Tried in 3 different outlets, with and without surge protectors, and once with a ups. Still the same

 

[ActionableMango]

Sounds like a dying power supply or something shorting out.

Any diagnostic LEDs illuminated?