PowerMac G5 Attacks!

Discussion in 'Macintosh Computers' started by pdpfilms, Jul 28, 2005.

  1. pdpfilms macrumors 68020


    Jun 29, 2004
    Ok, so we all remember the power supply issues from the rev. A Powermac G5's.


    Well it just came back from the dead and bit me in the butt. I've been running a Rev. A dual 2 ghz refurbished PM for as long as they've been around. I've noticed that power supply noise in the speakers before... sort of small clicks and stuff. But it never annoyed me enough to do something about it, as I heard much of the time a power supply replacement did diddly-squat anyhow.


    Today I brought my G5 to a place I'll be staying for a while, and connected everything in the same fashion it had been at the other house. (G5 plugged into UPS backup, nothin unusual.) When I turned the computer on, however, a nasty noise started eminating from the belly of the beast. It sounds like high-power electrical lines buzzing... a constant never changing buzz that's very noticable even when playing music.

    Here are the facts:
    -It goes away when i put the computer to sleep. (therefore NOT the UPS.)
    -It is there when the computer is plugged directly into the wall (Again, NOT the UPS.)
    -My computer used to take about 15-20 seconds to sleep, now sleeps instantly. (since transport.)
    -I have a PCI SATA card installed. (random, though it may have to do with it.)

    Here are my questions:
    -Is this the problem that everybody was whining about? Or was it the small clicking noise audible in the speakers?
    -Could something have happened in transport? It was only a short drive, and i did all the handling of the computer myself, no dropping or anything.
  2. TMA macrumors 6502a


    Jan 6, 2003
    - There are 2 issues around Powermacs surrounding PSU/CPU noise (chirps/squeeks) The first issue is that some Powermacs would have interference that you could pick up on the audio out. I believe Apple are classing this as a fault, as it can effectively ruin music production as well as spoil general use. I've read people saying they've had replacement PSU's to fix this problem.

    The second is that the noises are also audible when just sitting at the computer or being near by. The large heatsink attached to the CPU's acts as an amplifier. The G5 chips employ a technology that rapidly changes the state of the cpu in varying states of speed. When a part of the CPU is not needed, it will shut down. This happens very rapidly (hundreds of times a second?) and each time it does, different power levels are needed from the PSU. The oscillating effect of changing power levels causes the chirps/sqeeks and is then amplified through the heat sink.

    Using the energy saving preference panel you can alter the processor performance. Highest gives you the loudest noises. Reduced is the quietest and using Automatic you can only really hear the noises when the CPU is under heavy load. Apple's CHUD tools also allow you to disable 1 CPU which will reduce the noise and also will allow you to disable "NAP" (the technology that switches the cpu's speed many times a second) Doing this will completely remove chirps, but is not recommended by Apple and the setting has to be applied after each restart.

    My G5 Dual 2.0 has never suffered noises through speakers, and I don't think this is normal.

    - It's doubtful anything happened in transport, if something got damaged I think you would be experiencing more apparent problems

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