Power Mac G5 doubt

Discussion in 'PowerPC Macs' started by tokiacop, Jun 26, 2015.

  1. tokiacop macrumors newbie

    tokiacop

    Joined:
    Feb 12, 2015
    #1
    Hello to everyone!

    I was thinking... What could be the consequence of using the SMC Reset Button on a Power Mac G5
    (early 2005) 2 x 2.7ghz several times ? I use it with AC plug, AC unplug, one time, two time, keeping press for 30 sec, etc.. If i broke my mac by doing this , what would be the exact consequence ? What part of my hardware would be affected ?

    I question this because i was testing a Power Mac G5 that i received like a gift because the owner was going to discard, so... First time i plugged in, the Mac boot ! but with the fans at full speed i reach the desktop and immediately turn it off. 1 min later turn on the mac again and no more boot and black screen and no chime. Never boot well again! Always gets black screen! but.... i always get the power white led on. I probe to disconnect the Hdd, the DVD unit but no luck. Also probe the memory, diferrent combinations but nothing makes boot the Mac again. While i was testing the memory sometimes with a wrong combinations the mac give me 2 or 3 blinks in the white power led, but ALWAYS get the white led on and sometime chimes while doing tests!

    I found the Pram battery in 0 volts, so, i change it immediately for a new one and along with that i start to play around with the SMC Reset Button!! After that... The Mac never show me again the power white led on! The mac turn on like always but no more white led on! it`s just death! I think with that button i made it worse! Something happens after i play around with that button! and it`s a shame because i found that the video card maybe is not working properly, so.. i only worse the situation i`m very obfuscated..:(

    What do you think ? Any Ideas?

    Thanks for your time
     
  2. Altemose macrumors G3

    Altemose

    Joined:
    Mar 26, 2013
    Location:
    Elkton, Maryland
    #2
    @tokiacop The rapid fan use is likely a result of a removed and reinstalled CPU. The CPUs may have been removed at one point or knocked out of whack and therefore it needed a thermal calibration. It could be that CPU A was acting normal and now acts up. Any number of things could cause the symptoms you mention but the button should not have any negative effects. PowerPC Macs do not have an SMC but rather a SMU or PMU. You can read up some information on what the SMU button does on a G5 here.
     
  3. tokiacop thread starter macrumors newbie

    tokiacop

    Joined:
    Feb 12, 2015
    #3
    Thanks Altemose for your answer. Yes! is SMU Button! my mystake when i type , sorry.
    Ok then, i discard the fault because the use of that button, i gone to disassemble the CPU unit and put it back to see what happens . The power mac g5 can boot with only one cpu connected ? in that case, wich of the two should be connected?
     
  4. Altemose macrumors G3

    Altemose

    Joined:
    Mar 26, 2013
    Location:
    Elkton, Maryland
    #4
    @tokiacop A G5 can boot with CPU A installed, which is the top one. You can also place CPU B in where CPU A is for testing purposes, but the machine will need to be thermal re-calibrated either way.
     
  5. tokiacop thread starter macrumors newbie

    tokiacop

    Joined:
    Feb 12, 2015
    #5
    Ok! i gone to test and post the results! Thanks
     
  6. tokiacop thread starter macrumors newbie

    tokiacop

    Joined:
    Feb 12, 2015
    #6
    Helloo!

    You know that i found one CPU with a little small remaining of liquid leak, but the other is immaculate!
    i put aside the one with liquid and only plug the good one (in theory) in CPU A slot to probe if the computer start
    and the rest of the hardware is ok, but won`t start ! is like the computer were unplugged from AC , nothing happens!

    If i put it back the two CPU at the same time then begins to turn again but with said failure. The CPU A Slot is the more closer to AGP port right ?
     
  7. Altemose macrumors G3

    Altemose

    Joined:
    Mar 26, 2013
    Location:
    Elkton, Maryland
    #7
    Yes.
     
  8. tokiacop thread starter macrumors newbie

    tokiacop

    Joined:
    Feb 12, 2015
    #8
    Ok thanks, what could be the reason that when i put only one CPU (the good one) in CPU A Slot the computer
    no turn on at all like it was unplugged from AC ? Must configure something else to turn on the mac with only one CPU ?
     
  9. Altemose macrumors G3

    Altemose

    Joined:
    Mar 26, 2013
    Location:
    Elkton, Maryland
    #9
    @tokiacop Running on one CPU works for me and my dual 1.8 GHz model but it maybe different for newer machines with higher clock speeds or there is a different underlying issue.
     

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