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Old Jul 28, 2009, 07:12 PM   #1
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PowerMac G5 Dual Processor, no display, loud fan noise

I am having start up issues with my G5. It's a dual processor 2ghz... the ones that had the liquid cooling systems.

The fan noise has been very loud lately.
Once or twice it has shut down on its own after doing some loud fan noise stuff... did that last night... went totally off in the middle of an email typing.

And now when I start it up... there is nothing on my 23" display.
It chimes the first time and the lights come on and I hear the fans start to spin and it sounds like the hard drive is being accessed.

The keyboard doesn't respond so it will not let me do a PRAM reset. It's like it's asleep maybe. The monitor light is on... but nothing shows on the display.

I've read several posts about things to try.

I have so far:
- tried zapping PRAM but it never chimes the second time.
- opened it up and pressed the PMU reset button
- took the logic board battery out for about 30 minutes

None of these things changed anything.

Also when I look through the grille on the front of the machine I can see the red led light that some others have reported. Don't know if I've ever noticed that before or if it is relevant.

The machine is coming on... so I feel like it is fixable... just no display and nothing seems to be working as in the keyboard or mouse etc.

I have checked to make sure the cables are connected securely.

My g5 is not in the range of serial numbers that are in the g5 power unit repair program. It's just slightly off of some that are listed.

There IS some dust in there. I will try blowing that out as some have suggested that may help.

But I was wondering if anyone had any other ideas of what to try?

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Old Jul 28, 2009, 08:13 PM   #2
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I have a light when my G5 comes on, and it works perfectly - you may want to consult the manual if you still have it, in there there is a list of LEDs that will come on and if they are normal or not. I know that one being on for my model is the norm - you may also want to try booting with the case open and looking for that LED and seeing if it is labeled.

Furthermore, maybe a stick of your RAM died If you have more then two pairs of RAM, take out one pair and then reboot. If the problem persists, swap pairs. The instructions for doing so are in the manual if you have not done this before - since the RAM has to be in the right slots.
MacPro 4.1 | Powermac 11.2
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Old Jul 28, 2009, 08:17 PM   #3
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If you can hear the HDD working and loading the OS as normal but you don't see anything on the screen, it would sound like something is wrong with the video card. Do you have a spare card to test the system out with?
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Old Jul 28, 2009, 10:39 PM   #4
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Yes reseat the video card first.

Neither the 2.0ghz Dual processor

nor the 2.0 Dual Core

Powermac g5s were liquid cooled.

Sounds like you have the earlier dual processor machine and I believe these were plagued by faulty logic boards.

I have also heard that the thermal paste on the boards/CPU etc., is an issue for Powermacs as well as laptops. Google around may just be a poorly seated cpu.
2.66ghz 13" MBP/1.67ghz Powerbook G5 15" DLHR/iPhone 16gb/30" ACD
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Old Dec 25, 2009, 11:33 PM   #5
xenoc 157
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fixing the red light/constant fan problem G5 Mac

I fixed this by opening the side panel then removing the inner plastic panel and smoothing out the white electromagnetic tape on the inside of the back tab. Then carefully replaced the plastic panel ensuring that the back tab seated properly. Apparently, the tape on the tab is sensed by the Mac to confirm that the plastic panel is in place. If this is not sensed correctly, the red warning fan light comes on and the fan runs at constant high speeds. I spent hours reseating cards, cleaning dust bunnies, resetting PRAM and SMU, etc before finding this simple solution!
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Old May 18, 2012, 09:14 AM   #6
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Fixed it

Fixed the same issue On my computer. Fried video card. The fans would click up and wouldn't stop, black screans. Replaced the video card and everything is back to normal.
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