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Power Mac G5 (Late 2005) won't turn on.

I picked up a used Power Mac G5 2.3 Dual Core really cheap. I was told it was working but included no hard drive. It was in poor physical condition, however. Scuffs, scratches, dings and loads of caked-on dirt inside. Before I ever hit the power switch once, I knew I had to give it a good cleaning. I disassembled all parts and removed all the dirt with great care. I even had to treat some parts that were contaminated with rust (CD-ROM shield). It was obvious that the owner lived near a lot of moisture. 😮

It only took a weekend, but I got it all back together and looking fairly decent. I connected a monitor and hit the power button. It came up! I then worked on getting a compatible SATA drive. I did not realize it at the time but a SATA rev 3 wouldn't work. I found a rev 2 and it was recognized. I installed Leopard and took care of all the updates. All seemed well for about a week.

Then one morning I was awaken by a loud clicking sound coming from the room with the G5. I confirmed it was the G5 and also observed that the power LED would flash while the clicking noise was going on. I tried to "wake up" the Mac thinking this could be some weird sleep problem but it didn't respond to mouse or keyboard input. I then pulled the plug and the noise ceased. I waited a little while and plugged it back in and both the noise and the LED flashing returned. No matter I tried, it would not power up, though.

I did some searching and came upon someone who suggested resetting the SMU as a possible solution to another's power problem. I did the reset and this seemed to stop the automatic clicking and flashing. When I tried hitting the power button, it still does not come up. I only see a momentary flash of the power LED and then a "clunk clunk" noise -- the same noise I was hearing repeatedly before.

So this is where I am. Is there anything else I can try or should I conclude that the power supply is dead? That would sure be a disappointment considering the stressed environment the machine had to put up with, now getting the proper attention it deserves only to then decide to die on me. 😟

Posted on Jun 25, 2013 9:13 PM

18 replies

RatVega™

Level 4

2,005 points

Jul 2, 2013 11:28 AM in response to Jeff Robertson

Jeff Robertson wrote:

If bent processor pins were involved, I don't think I could have gone as long as I did before the trouble started. I would have had the problem I very first time I tried to turn it on.

I agree completely. I missed something in your messages... mea culpa.

The value I place on the machine wouldn't be worth a trip to have it professionally diagnosed, sadly.

I'm sure getting someone to even being in the same room with the machine would be cost prohibitive.

I think my guy charges $85/hr.

Since I have already removed the processor once and had planned to again to replace a possible bad power supply, perhaps I will take a look for myself and see if I find any bent pins. I'm sure they would be obvious to locate with the unaided eye.

I think I'd be wearing magnifying glasses... the socket is 5/8" X 1-5/8" and has 300 pins

Incidentally, I would like to also replace the thermal compound if I ever get to that point. If the processor module itself is sensitve to handling, taking it apart to replace the compund must just be asking for trouble. This is something I've done countless times with your avergae PC, mind you, so I have no fear with taking on the G5. I just don't want to make matters worse if I offend it with the smell of my breath. 🙂

I can't speak to thermal compound, all my G5s are liquid cooled (How else could I have gotten them all rebuilt at no charge after the warranty expired?)

Good luck!

Jul 12, 2013 10:05 PM in response to RatVega™

Well I found a matching power supply on eBay and just finished installing it a short time ago. The machine is turning on now, but all I am seeing is a white screen come up, no beep, no hard drive activity and then after a little while the fans start running very high. Since this seems like an undesireable thing to allow to continue, I force down the machine by holding the power button.

In my past google searches trying to sort out my original problem, I came acorss this scenario many times.

Anyone want to help me cut to the chase and tell me if there is a quick way to get around this? Perhaps another SMU reset is needed?

Thanks.

Jul 13, 2013 9:06 AM in response to Jeff Robertson

False alarm. It was just a loose power cable connection to the media bay. Booting up fine, now.

So, it would seem there was a bad power supply.

Power Mac G5 (Late 2005) won't turn on.