Early 2008 Mac Pro intermittently not starting

Remove side cover and run mac, you might see some red lights on memory or somewhere else.

You could check the voltage in the outlet to confirm if you have a voltage issue. There are "easy" checking tools that you can buy and plug into the outlet, but those would only tell you if the outlet was wired correctly. You would want to check it with a voltmeter that has the metal prongs on it. You should be getting 120 from hot to neutral, 120 from hot to ground, and 0 from neutral to ground when you test the different slots on the plug. You would want to do this sometime when the computer is acting up so you could rule out a problem outside the computer.

Otherwise you could have some RAM that is acting up. Try removing and swapping your RAM in and out to see if you have a bad piece. I've had several pieces go bad in my 2008 over the years - luckily I always bought it from reputable places that would replace it no questions asked. The special RAM with the heat sinks that the 2008 requires is one of a few crappy things about that model.

has it been on a UPS all along?

As for memory I have found Nemix to run much lower temperature and excellent price. You can use 667MHz which costs almost half as much.

And maybe it just needs to be unplugged, all cables, hit power button, and you could have even a bad USB extension or keyboard but SMC Reset and NVRAM (cold boot) would be in order.

rouxeny said:

I have also unplugged the computer before and had it sit, with varying results.

Also tried booting wrong the graphics card in, no different.

Click to expand...

Never seen where leaving unplugged made any difference, either.
Hitting the power button while unplugged has.

FBDIMMs fail if they are subject to heat over time and it exceeds 72*C which what makes the NEXIX so welcome.

Then again, the 3,1's do seem to stand out in how much disorder they exhibit.