Previous 1 2 Next 18 Replies Latest reply: Jul 13, 2013 9:06 AM by Jeff Robertson
Jeff Robertson Level 1 (15 points)

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. 

  • kaz-k Level 5 (4,390 points)

    About the PowerMac G5(late 2005) diagnostic LEDs.

  • Jeff Robertson Level 1 (15 points)

    Yeah, I've seen the diagnostics LED chart. None of those apply in this case.

  • BDAqua Level 10 (122,286 points)

    Did you blow dust out of the Power Supply real good?

  • Jeff Robertson Level 1 (15 points)

    As much as possible. I do not believe the power supplies are meant to be open. But, you can tell there was a lot of dust infiltration by looking through the fan blades. I'm leaning in the power supply replacement direction right now. Just need to find a good source for one at a reasonable price.

  • BDAqua Level 10 (122,286 points)

    I do think that's likely the right path.

  • Jeff Robertson Level 1 (15 points)


  • Jeff Robertson Level 1 (15 points)

    My power supply search has raised more questions. I have the 1000W version, but I'm wondering if I could get by on the 710W instead. The 1000W would appear to be intended for Dual Processor G5s, whereas I just have a single, Dual Core. The extra grounding lead for the second processor goes unused in my machine. Perhaps the original owner replaced the power supply before.


    The only possible reason for me to seek out another 1000W unit would perhaps be in support of a beefier video card, which I am also interested in getting....if I can even find one (Nvidia 7800 GTX).


    Can anyone shed some light on this?



  • BDAqua Level 10 (122,286 points)

    Either way, 710W for 2.0/2.3 models and 1000W for the Quad is right on the money. The 2.0/2.3 models being able to use the 1000W PSU if required.


    +Part: 661-3737+

    Power Supply, 710W for Dual Core 2.0ghz- 2.3 ghz.

    Delta DPS-710BB A (614-0368) , ACBEL API5FS17(614-0367)


    +Part: 661-3738+

    Power Supply, 1000W for Quad Core 2.5Ghz. Also for Dual Core 2.0ghz- 2.3 ghz. ACBEL API4FS13 (614-0384, 614-0373)


    Cheers, R.


    450watt & 600watt have different connectors.


    Archived -  Power Mac G5 (Late 2005): Power consumption and thermal output (BTU) information...





  • RatVega™ Level 4 (2,005 points)

    First, try removing the power cord from the chassis and leaving it disconnected for several hours and then replace and try to restart.  One of my 2.5GHz G5 dualies requires this if it is out of use for more than a few days, and it takes overnight. Has to do with a weak PS component...


    Unfortunately, the power supply for the PowerMac G5 is buried at the bottom of the chassis and AFIK requires that the processors be removed to access it. This amounts to major surgery (at least im my eyes.)


    My (Apple Authorized) independent service person is highly competent tells me it's very difficult to remove/replace the processors without bending a pin (there are about 300.) And if you get it back together and it starts, you'll need the thermal calibration software that is restricted to Apple Authorized Service techs.


    Not good news, but you need to know.

  • Jeff Robertson Level 1 (15 points)

    Thanks for the info. I will give that a try.


    No problem on the processor removal as I have already disassembled the machine for the initial cleaning. According to the instructions I followed regarding the processor, there was no mention of the requirement for calibration. It did clearly indicate the need to be careful about not bending pins, howver, and I believe I have complied with that. The biggest challenge I had there was finding the correct torx driver with a long enough shaft to make it through the holes in the heat sink.


    That is interesting, however, since I was doing something with demand on the CPU the night before it starting giving me trouble. Perhaps there was a thermal shutdown event and it has never recovered from it. I was monitoring the CPU temps while the encoding was going on the they seemed very moderate, though.

  • Jeff Robertson Level 1 (15 points)

    As it turns out, I already had the power cord plug removed for the last three days. Reinserted it and hit the power change. Sigh. I had hope on that one.

  • RatVega™ Level 4 (2,005 points)

    I have one 2.5GHz G5 dualie that has had the processors replaced twice and three logic boards. I was under the gun when the last repairs were done, so my repair guy gave me a copy of the thermal calibration software and I did the work myself (we understand each other...)


    It may be possible that under certain circumstances the calibration will be correct, but my systems have always required it. The nature of my repairs has been processors, logic boards, liquid coolers, and power supplies.


    If you got into your 2.3GHz cheap and you've got a geeky side, it may be worth a try.  I keep a couple of Husky 8-in-1 screwdrivers (SKU 3165 355 #4-#10 +#15 Torx & SKU 163 149 #000-#1 Phillips & 1/16 - 1/8 slotted) handy for disassembly work. They're in expensive and work great! I got my latest sets on Amazon for ≈ $6 each.

  • Jeff Robertson Level 1 (15 points)

    Not sure where I would even go to for that. Would an "out of calibration" processor exhibit the behavior I am seeing? It could prevent a machine from turning on?


    Doesn't seem like there is enough time for the state of the processor to be determined if there are no other signs that life coming from the machine. It is not as if it is coming on briefly and then shutting down. It isn't coming on at all.

  • RatVega™ Level 4 (2,005 points)

    Don't let the technospeak unhinge you; the short version of "thermal calibration" is that it uses thermal sensors within the processor to make sure the fan system runs as designed. As near as I could see in my limited exposure, the software runs a series of scripts and then writes a "profile" which makes the fan controller do its thing correctly. A calibration run takes about a half hour as I recall.


    One of the issues associated with bending the processor pins is a "no start" condition. That said, there are a lot of other possibilities. If your nerve is crumbling (mine would be about now) then find a reputable Apple Authorized service guy and pay for a diagnosis. I would not go to an Apple store over a PowerMac or Mac Pro problem; most are really not equipped to handle this level of system. They're fine for iToys. Apple has a locater for their independent service guys on their website.


    Good luck.

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