Early 2008 Mac Pro intermittently not starting

rouxeny

macrumors 6502
Original poster
Jan 22, 2008
264
4
Hi guys, I have an early 2008 Mac Pro, it's been a great computer, but over he past few months, it's started having some problems. First, it would randomly turn off when sleeping. I'd leave it on for the night and come back to it off.

Now, it's having difficulties starting. Sometimes, it's entirely fine. The other times, I push the power button, it clicks (as normally would), then silence for 2-3 seconds, then it clicks against and is off. The power light does not turn on, I don't hear anything going on in the computer.

I've reset the PRAM to no avail.

I am suspicious it's the power supply, although I don't know why it would still work sometimes if that was the case.

I've also cleaned out the computer, there's minimal dust.

Any ideas?
 

netkas

macrumors 65816
Oct 2, 2007
1,122
292
Remove side cover and run mac, you might see some red lights on memory or somewhere else.
 

rouxeny

macrumors 6502
Original poster
Jan 22, 2008
264
4
Good suggestion.

I get nothing, no lights on at all.

The area where I live does not seem tomalwaysnhave the most consistent power. We have a lot of random power outages.

I have tried both with and without a power strip.
 

flehman

macrumors 6502
Feb 21, 2015
349
188
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.
 
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rouxeny

macrumors 6502
Original poster
Jan 22, 2008
264
4
I haven't noticed any other issues with low voltage, so I have some difficulty believing it is the problem.
 

IowaLynn

macrumors 65816
Feb 22, 2015
1,311
289
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

macrumors 6502
Original poster
Jan 22, 2008
264
4
I have tried booting with each of the memory risers out, no change. When the computer has booted before, there are no issues with the memory.

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

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

IowaLynn

macrumors 65816
Feb 22, 2015
1,311
289
I have also unplugged the computer before and had it sit, with varying results.

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