1 CPU running hotter than other on Quad G5

jherrlingjherrling
Posted:
in Genius Bar edited January 2014
I've had a problem recently that seems to be getting worse lately in that CPU B is running anywhere from 20-40 F hotter than CPU A. Both cores are registering this temperature so I don't think it's a sensor issue unless both are bad. I can also can raise the temp of the cpu to over 200 F while running folding or similar software, and this is a sustained temp for 10 min. The fans and water pump speeds were at their max values according to Hardware Monitor and a widget I have, iStat Pro or something similar.



I'm just wondering if anyone else has had this issue and what if anything apple has done about it and what might be the cause of it. Also what would be the cause of this, loose heat sink perhaps? I blow the dust out of the insides about monthly but I have not noticed it affecting the temp issue.



Thanks

Comments

  • Reply 1 of 4
    altivec_2.0altivec_2.0 Posts: 995member
    First what you need to do is open up your mac and check the heatsinks on your cpus's. My guess is that one is packed full of dust. Sometimes if one processor is used more than the other the fans on that one cpu will run more than the other, sucking up more dust, etc.. check that out.
  • Reply 2 of 4
    chris vchris v Posts: 460member
    CPU A has always run about 10º F hotter than CPU B on my dual 2.0. Don't know what the normal variance is, but 40º seems a little much, uless you're running something that only takes advantage of 1 CPU, but maxes it out for lengths of time. Have you taken a look at Activity Monitor to see what's running, if the actual load is heavier on one CPU than the other?
  • Reply 3 of 4
    goran larssongoran larsson Posts: 5member
    Quote:
    Originally Posted by jherrling


    I've had a problem recently that seems to be getting worse lately in that CPU B is running anywhere from 20-40 F hotter than CPU A.



    This is a problem with some of the early G5 quad systems. The problem is that something goes wrong inside the processor/cooling module and the liqud cooling system is then no longer able to remove the heat from one of the processors. The high temperature activates the fans, but that doesn't help. My quad had the same problem and is currently repaired under warranty.



    I wrote a document with a description of the problem to help the repair center. It can be downloaded from my site: http://www.mitt-eget.se/G5_Quad_cooling_problem.pdf.
  • Reply 4 of 4
    jherrlingjherrling Posts: 80member
    Quote:
    Originally Posted by Göran Larsson


    This is a problem with some of the early G5 quad systems. The problem is that something goes wrong inside the processor/cooling module and the liqud cooling system is then no longer able to remove the heat from one of the processors. The high temperature activates the fans, but that doesn't help. My quad had the same problem and is currently repaired under warranty.



    I wrote a document with a description of the problem to help the repair center. It can be downloaded from my site: http://www.mitt-eget.se/G5_Quad_cooling_problem.pdf.



    Thanks just what I needed to know and my system was one of the early systems.



    I've also tried everything including using CHUD tools to not use that CPU but it still idles warm. Even at idle with everything on reduced the fans are still running with one cpu at 84F and one around 115F. So it has to be a hardware issue I think.
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