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Apple Desktops Discussion of Apple's desktop machines including Mac Pro, iMac, Power Mac, and mini

Early 2008 Mac Pro won't power up


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kevvo

 
Member Since: Sep 22, 2010
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I have a Mac Pro from mid 2008. Recently, it has done the following:

Also, it will now sometimes just power off completely without warning.

Problem 1: In the morning when I turn it on, on some occasions it will power on for 5 or so seconds, then power right back off again. Sometimes this happens after 5, 10 or even 20 seconds (right in the middle of OS X or Windows boot). This can sometimes happen 10 or 20 times in a row before it will eventually turn on and function normally.

Problem 2: Random power cut off, sometimes at idle, sometimes while browsing, or using any other app. I can't pin it on any one particular function. I know it's not a temperature problem, I have temp monitors on my menu bar and as far as I can see it's been fairly stable in that regard. Most of the time, I can power up the computer again but very occasionally it will revert to what I described in problem 1.

I had it checked out by an engineer who got it running, and ran diagnostic tests on a loop. No problem. Then took it home and problem 1 re-occurs!

One further piece of info, boots up fine if I remove the power cord overnight.

Any advice, or others who have had this problem would be much appreciated.
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chscag

 
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The random restarts could be caused by several things: The most common is a power supply which is failing, the second is flaky memory. You should be able to isolate any memory problems in that machine fairly easily, so that's where I would start. The power supply is going to be more difficult since about the only way to trouble shoot it, is to replace it.
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kevvo

 
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Quick update...

Re-installed OSX and updated over the weekend. Since then, it now sleeps normally (ie without switching off completely) and has powered up effectively. I'll watch it over the next couple of days, but seems to have done the trick for the time being. Very strange.
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kevvo

 
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Hmmm....had nearly a week of good performance, and then the error reappeared again yesterday...power up then straight back off again. Also, when I do manage to get the MP to power up, when I use the sleep option, it powers down again.

Strange...
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chscag

 
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Maybe time to replace that power supply?
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ioio

 
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I have the same issue. Took it in to test it, all components work and tested fine, even the power supply. Stumped. Logic board is the only thing left. Anyone has resolved this issue. Any help appreciated.
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Power Supply most likely culprit. It will work like you describe, and then fail for no reason. Have you opened the Mac Pro and given it a good clean out lately?

Hang on to those original install discs like grim death! Using OS X.7 or later make a bootable USB thumb drive before running Installer!
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LRS

 
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Quote:
Originally Posted by kevvo View Post
I have a Mac Pro from mid 2008. Recently, it has done the following:

Also, it will now sometimes just power off completely without warning.

Problem 1: In the morning when I turn it on, on some occasions it will power on for 5 or so seconds, then power right back off again. Sometimes this happens after 5, 10 or even 20 seconds (right in the middle of OS X or Windows boot). This can sometimes happen 10 or 20 times in a row before it will eventually turn on and function normally.

Problem 2: Random power cut off, sometimes at idle, sometimes while browsing, or using any other app. I can't pin it on any one particular function. I know it's not a temperature problem, I have temp monitors on my menu bar and as far as I can see it's been fairly stable in that regard. Most of the time, I can power up the computer again but very occasionally it will revert to what I described in problem 1.

I had it checked out by an engineer who got it running, and ran diagnostic tests on a loop. No problem. Then took it home and problem 1 re-occurs!

One further piece of info, boots up fine if I remove the power cord overnight.

Any advice, or others who have had this problem would be much appreciated.
I have the same issues,
have replaced, or tested replacing
psu
heat syncs
both cpus
and finally the logic board.
Resolved it for 3 months, then the same thing happened.
There's something chronically wrong with a percentage of this era of machine from a manufacturing standpoint. IMHO
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LRS

 
Member Since: Jul 15, 2012
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I have the same issues,
have replaced, or tested replacing
psu
heat syncs
both cpus
and finally the logic board.
Resolved it for 3 months, then the same thing happened.
There's something chronically wrong with a percentage of this era of machine from a manufacturing standpoint. IMHO
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