A crater-like dent on G5 processor?

Discussion in 'PowerPC Macs' started by iamMacPerson, Jul 19, 2014.

  1. iamMacPerson macrumors 68030

    iamMacPerson

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    #1
    So a friend gave me a set of 2.7GHz G5 cards to put in my G5, which I did. Once I did, the machine refused to boot and I blamed it on the processor pulling too much power. Well, I tore the machine back apart to reinstall the original 2.0s and noticed there was this crater/dent/chip/hole on the die it's self. Not the card, the die. I was wondering what might cause this and could this have been the reason my G5 wouldn't boot from them?

    Thanks!
     
  2. Intell macrumors P6

    Intell

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    #2
    The first problem is the CPU/logicboard mismatch. G5's will rarely, if at all, boot with CPUs other than what their logicboard shipped with. Their fbus is locked to a certain speed that is dependent on the CPU's speed. Without that speed, the board panics and doesn't post or it will put the CPU's in a sub-1Ghz fail safe mode. Any damage to the silicon die will cause the CPU to be unusable.
     
  3. iamMacPerson thread starter macrumors 68030

    iamMacPerson

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    #3
    That problem with the fbus would explain a lot actually. I put in some 2.3s and it would POST and boot, however it would KP under any sort of load. I guess the 2.7s trying to move the fbus to 1.35GHz screwed it all up to the point where it wouldn't boot. Of course the damage to the die on CPU1 didn't help either.
     
  4. gavinstubbs09 macrumors 65816

    gavinstubbs09

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    #4
    I have to challenge this theory - I have a 2.7 machine that I put a 2.3 set into. The FSB changes to 1.15GHz whereas the 2.7 was 1.35GHz. Even running geekbench, the system scored 2064 and the stock 2.7 scored 2363. Had the processors been in the "locked" 800MHz, wouldn't my geekbench be sub 1400 if they were acting as dual 800MHz? I have yet to have this machine lock up with these processors.
     
  5. Intell macrumors P6

    Intell

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    #5
    Some of the boards will accept other similar CPU speeds, but a jump from 2.0Ghz to 2.7Ghz is too big of a jump. Other boards will refuse to boot with any speed but the speed it shipped with.
     
  6. sarthak, Jul 19, 2014
    Last edited: Jul 19, 2014

    sarthak macrumors 6502

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    #6
    Got any pics? It would be interesting to see how a damaged die looks like.

    As far as I am aware, G5 machines don't like processor swaps unlike the PM G4. Only if there was a way to flash the machine.

    The hard way to upgrade is to replace the board and chip (assuming it fits). It's more economical to pick up a higher spec machine than a new board from eBay.
     
  7. iamMacPerson thread starter macrumors 68030

    iamMacPerson

    Joined:
    Jun 12, 2011
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    #7
    Sure here you go!

    IMG_1381.jpg

    Regarding buying another machine, I know but I had access to these processors so I figured I would give it a shot. Right now I'm actually on a hunt for a Dual Core model (late 05) and I might actually know where I can get one.
     

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