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View Full Version : Mac Pro G5 Dual 2.0Ghz - Plug In To Power and Get Eternal Clicking From Power Supply


nj_computer_repair
09-15-2009, 05:26 PM
Pretty sure this is a bad power supply but just checking to see if anyone had a similar issue. The computer is a Mac Pro dual 2.0Ghz. When you plug in the power cord, you get the normal click that the power supply makes for this computer, but then it clicks again and again. This is without even pressing the power button on the front. The computer does not respond to any buttons although if you press the reset button on the motherboard and hold it, the clicking stops - only to start up again as soon as you let go. The front light on the power switch blinks also along with the status light on the mobo.

Anyone have this issue before?

14049752
09-15-2009, 05:36 PM
I'm about 99% sure that this was a known issue with these a few years ago. I think there were a BUNCH of them that had that problem right out of the box, too.
It was the power supply on those system.

anonymous Mac Tech
09-15-2009, 06:51 PM
You have to reset the PMU button on the logic board with the power unplugged. Give that a shot and see what happens.

nj_computer_repair
09-15-2009, 07:52 PM
"Unlike models of Power Mac G5 or Power Mac G4 computer, the Mac Pro computer does not have a PMU. This functionality has been replaced by the SMC."

http://support.apple.com/kb/HT1806?viewlocale=en_US

I tried to reset the SMC with the computer off to no avail.

One thing that was interesting: I unplugged the connector from the power supply that connects to the system board right by the SMC switch. The computer obviously did not respond to the power button on the front but there was no clicking noise when I plugged in the power cord. The lights on the logic board were on and not blinking.

The power supplies for this computer are not cheap so it might not be worth repairing this system.

anonymous Mac Tech
09-15-2009, 08:28 PM
"Unlike models of Power Mac G5 or Power Mac G4 computer, the Mac Pro computer does not have a PMU. This functionality has been replaced by the SMC."

http://support.apple.com/kb/HT1806?viewlocale=en_US


You said Mac Pro G5 in the thread title for which there is no such thing. I just went along like you meant a Power Mac G5 since you said its a dual 2.0 Ghz. Is it an Intel Mac Pro or Power Mac G5?

Some of the G5 towers had a button at the top right corner of the board for bypassing the power switch to rule out a faulty power button. You also might want to try reseating the processors. Then try removing the bottom processor and then try the bottom processor in the top spot because a bad/not correctly seated processor will show the same symptoms. Was the power LED flashing like no RAM was installed or flashing as the power supply clicked?

If its a Mac Pro check the video card for popped caps. Those things are famous for faulty video cards.

nj_computer_repair
09-15-2009, 08:49 PM
My b! It's a Mac Pro INTEL - sorry about that. I will try what you suggested and post back. Thanks for the tips!

14049752
09-15-2009, 09:04 PM
Yeah, I was going on it being a Dual G5 as well.... strike what I said.

You non-mac guys really gotta learn that not everything's a G5. :D

nj_computer_repair
09-15-2009, 09:19 PM
I am slightly embarrassed right now :o - in any case, the project is being scrapped. Thanks for the tips anyway guys. Next time I will proof read before asking for help.

14049752
09-15-2009, 09:24 PM
I am slightly embarrassed right now


Don't be! It's honestly an easy mistake to make..... It's just that it makes a ton of difference in terms of an answer. Tons of people call their new iMacs "G5" when I talk to them, so I automatically start remembering back to the failing logic boards and power supplies that plagued those system....only to find out that it's a new intel.

nj_computer_repair
09-15-2009, 09:35 PM
Just embarrassed because I've been fixing Macs for a while. I love Mac naming conventions. It's been a long day, time to unplug and have some scotch :D

anonymous Mac Tech
09-15-2009, 09:51 PM
Every time I get a phone call its a G5 macbook or macbook pro G4, you get the point! If I wasn't working on these things constantly I'd be getting the names wrong too.:D

Since its a Mac Pro I'm leaning towards power supply as well. The Mac Pros had some diagnostic LEDs for trickle charge and power supply verification althouugh I have yet to see those lights point out a bad power supply on those things. Just disconnect whatever you can and strip it down as much as possible just to make sure. Get back with us if you need some more tips on the machine.

nj_computer_repair
09-16-2009, 06:26 PM
Computer is fixed.

I disconnected the system board from the power supply, took out the video card, took out all the memory, disconnected the hdd. and dvd drive, took the power supply out to get some numbers off it - the customer wanted it fixed despite the cost. I decided to hook everything back up for one last go - same issue - what actually made this thing work was when I took the cmos battery out. Go figure. I suspect there was a short in that general area causing this thing to flip out. Reseated the battery and system is happy.

Thanks for the help guys.

anonymous Mac Tech
09-16-2009, 07:43 PM
Computer is fixed.

I disconnected the system board from the power supply, took out the video card, took out all the memory, disconnected the hdd. and dvd drive, took the power supply out to get some numbers off it - the customer wanted it fixed despite the cost. I decided to hook everything back up for one last go - same issue - what actually made this thing work was when I took the cmos battery out. Go figure. I suspect there was a short in that general area causing this thing to flip out. Reseated the battery and system is happy.

Thanks for the help guys.

Awesome! Thanks for keeping us posted. First I've heard of the battery flipping one of those things out so you've got one up on me. I know dead/not properly installed batteries would cause no power issues all the time with the G3 and G4 towers, but that's the first I've heard of it happening with an Intel. Glad it worked out!:)