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Old Feb 26, 2013, 03:54 PM   #1
heisenburg
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Bad power supply?

My 2008 Mac Pro refuses to power on, when I push the power button nothing happens.No lights or fans power on; it acts like it is unplugged, but it is not unplugged. I tested the power cord in an another machine, and it worked fine. At this point, I'm thinking I will need to replace the power supply. Has anyone else had this issue?
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Old Feb 26, 2013, 03:59 PM   #2
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Quote:
Originally Posted by heisenburg View Post
My 2008 Mac Pro refuses to power on, when I push the power button nothing happens.No lights or fans power on; it acts like it is unplugged, but it is not unplugged. I tested the power cord in an another machine, and it worked fine. At this point, I'm thinking I will need to replace the power supply. Has anyone else had this issue?
Try using a different power cord or plugging your Mac Pro to a different outlet. If nothing happens it may be likely your power supply. Is your Mac Pro plugged to a UPS with surge protector or plugged directly to the wall outlet when you are using this?
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Old Feb 26, 2013, 04:12 PM   #3
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Quote:
Originally Posted by heisenburg View Post
My 2008 Mac Pro refuses to power on, when I push the power button nothing happens.No lights or fans power on; it acts like it is unplugged, but it is not unplugged. I tested the power cord in an another machine, and it worked fine. At this point, I'm thinking I will need to replace the power supply. Has anyone else had this issue?
Try unplugging EVERYTHING from the machine (all USB, monitors, ethernet, etc.) then plug power cord directly into a tested & working outlet. If the machine doesn't power on at that point, then it's probably the PSU. Can try unseating all PCI cards as well, but that's only caused a power issue for me once on a PC many years ago.

If replacing PSU yourself, be sure to get the right part number, they're all a little different...
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Old Feb 26, 2013, 04:33 PM   #4
heisenburg
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Originally Posted by bsbeamer View Post
Try unplugging EVERYTHING from the machine (all USB, monitors, ethernet, etc.) then plug power cord directly into a tested & working outlet. If the machine doesn't power on at that point, then it's probably the PSU. Can try unseating all PCI cards as well, but that's only caused a power issue for me once on a PC many years ago.

If replacing PSU yourself, be sure to get the right part number, they're all a little different...
I just removed the power supply from my Mac Pro. I then opened the power supply (yes I know there are 450v capacitors). I then tested the fuse which was not blown. I noticed that there was scorch marks on the metal inside the power supply. Does this just happen over time from high temperatures, or did my power supply have a melt down?
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Old Feb 27, 2013, 02:59 PM   #5
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Make sure you do a SMC reset. Just means yanking the plug and then holding power button down for 5 seconds or so. Plug in again and hit power. Listen for click
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Old Feb 28, 2013, 02:42 PM   #6
heisenburg
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I see burn marks inside the power supply, so I assume, the power supply died. Do I have to get the exact same part number? The part number on my power supply happens to be the most expensive Mac Pro power supply there is. I see other Mac Pro power supplies with the same wattage and same power connectors, but they have a different part number. Will they be ok for me to use?
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Old Feb 28, 2013, 04:33 PM   #7
666sheep
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You need 661-4677 (614-0409). These with different part numbers have different (lower) amperage on 12V lines. There is used one for $140 on US eBay ATM.
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