Pheidius1

Q: Which CPU is CPU A and which CPU B

Hi all,

 

Quick question. Does anyone know which processor board is CPU A and CPU B? Is Cpu A the board on the bottom side or the board on the top side? As noted in a recent post of mine, I successfully pulled both boards and reapplied thermal paste but now my CPU B is running hotter than it did before. This time I just want to pull the offending board but I don't see which is which being identified in the service manual.

PowerMac, Mac OS X (10.5.5)

Posted on Apr 29, 2016 1:27 AM

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Q: Which CPU is CPU A and which CPU B

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  • by Limnos,

    Limnos Limnos Apr 29, 2016 5:15 AM in response to Pheidius1
    Level 9 (53,951 points)
    Mac OS X
    Apr 29, 2016 5:15 AM in response to Pheidius1

    Uh, apart from being a PPC we don't know which model computer.

  • by BDAqua,Solvedanswer

    BDAqua BDAqua Apr 29, 2016 6:08 PM in response to Pheidius1
    Level 10 (123,633 points)
    Apr 29, 2016 6:08 PM in response to Pheidius1

    As i recall A is the top one.

     

    Did you Thermal Calibrate after redoing the paste?

     

    Were the CPUs replaced in the same sockets as before?

  • by Pheidius1,

    Pheidius1 Pheidius1 Apr 29, 2016 3:36 PM in response to Limnos
    Level 1 (15 points)
    Desktops
    Apr 29, 2016 3:36 PM in response to Limnos

    Hi Limnos. Excuse my not posting which model I have. This one is the quad 2.5 edition. I thought that people reading this might have read my howto in my previous post but that was dumb now that I think of it.

  • by Pheidius1,

    Pheidius1 Pheidius1 Apr 29, 2016 4:02 PM in response to BDAqua
    Level 1 (15 points)
    Desktops
    Apr 29, 2016 4:02 PM in response to BDAqua

    HI BDAqua,

     

    You and I had a thread together on the issue of high temps on CPU A. I could not use the howto link you sent me once I got in because my model was different than that author's. Fortunately my model was far easier than that one and I posted a how to here.  I think i called it quad 2.5 thermal paste.  I have not yet run thermal recalibration yet as Arctic silver(all versions) specifies a break in period that can be as long as a month for some chips. I suspect that if I run it now, it will quit without making changes  because of the 8 C disparity of the dies at idle. At fifty percent load for extended periods(overnight) in a non air conditioned room the disparity drops down to about 2-3 C 52ish on CPU A and 56 ish on CPU B. The fans, however, are running at half speed(annoyingly loud).

     

    In answer to your question: No, I did not change the location of each board as I did one at a time to have an adjacent reassembly model. I did, however, mess up and boot the machine without the nvram battery and it booted but ran with even higher fan speeds. I did run the full battery of OF tests and it checked out fine save two bad pieces of memory. It balked twice at running the CPU  A pump fan test but passed on the third go.  The machine now boots to normal fans but they instantly rev up as you login. I sent an email to Arctic silver begging them for PPC application instructions so I don't expect much from that direction.

     

    On the bright side, If I do this again I will make a pictorial howto and see if one of the mac devoted sites will publish it. This morning i realized I do have a way to confirm your memory of CPU A being on the upright topside. I can just run the CPU A and CPU exhaust fan OF test and should detect with my hand each fan shutting down and then restarting.  I was just hoping someone had a link as this job, while ultimately pretty easy)on my model, is not one I care to keep repeating. CPU A is fine and I want to leave it alone and only focus on the one that is now out of line.

  • by Pheidius1,

    Pheidius1 Pheidius1 Apr 29, 2016 11:49 PM in response to BDAqua
    Level 1 (15 points)
    Desktops
    Apr 29, 2016 11:49 PM in response to BDAqua

    I can now confirm your memory that CPU A is the top card and B is on the bottom, I confirmed this by using ASD 2.6.3 to run just two tests; CPU B exhaust fan and CPU A exhaust fan. I Just used my hand to feel which fan turned off then back on again.

  • by BDAqua,Helpful

    BDAqua BDAqua May 2, 2016 4:02 AM in response to Pheidius1
    Level 10 (123,633 points)
    May 2, 2016 4:02 AM in response to Pheidius1

    Thanks, I can't be 100% sure on my memory anymore.