Problems after 2009 Mac Pro CPU Upgrade!!

Discussion in 'Mac Pro' started by Status42, Jun 22, 2015.

  1. Status42 macrumors newbie

    Oct 12, 2011
    Dear all,

    After reading many threads here, and this one too ( and watching a great youtube film by Lance MacV about this I undertook the CPU upgrade going from a dual 2.66 8 core to a dual 3.06 12 core. I bought Arctic 5 thermal paste and thermal material to account for the difference in thickness between the old CPUs and the new ones. I also applied the Firmware update so I could run the faster 1333MHz memory. I pretty much did what many had done before.

    Everthing went well. My 4 memory chips were seen and the CPU were also working on the first reboot which was amazing. The only thing I noticed was the FAN on heatsink A was not running so that the fans whirred very fast on boot. I could see this from using a utility called Mac Fan Control. See the screen grab.

    So I took the Heatsink off removed the CPU stuck to the bottom and tried to see if the was a problem with power cable. I unstuck black cable on the bottom of the heatsink to give me a little extra play in the cable length. Now when I restarted my Mac the Fan still seems not to be working and all the fans whir to maximum but the memory in slot 1 on the motherboard is now not being seen - so I've got 12GB active. I tried many difference amount of turns of the heatsink screws but I've still got the same problem. So are there any other things I can try or investigate? I've done SMC reset. IS it possible I've damaged the black power cable on the bottom of the Heatsink with out knowing it? Does that cable provide another function?

    Any help would be very gratefully received.

    Mac Pro Fans (2009).jpg
  2. Status42 thread starter macrumors newbie

    Oct 12, 2011
    Does anyone know of anything I might try here?

    Or can anyone tell me what the black cable does on the bottom of the heatsinks? Is it a power cable? In the MFC screen grab the fact there's no readings for CPU A means something is wrong I fear? Does anyone know?

    Apologies for all the questions but I'm slightly in the dark now.

    Thanks in advance for any help.

  3. box185 macrumors member


    Sep 12, 2013
    I suggest reading the page you referenced in your first post . . . again.

    • Each heat sink (there are two in 8-core and one in 4-core machines) contacts a socket on the processor board (daughterboard) when it is installed which conveys temperature data to the fans. This socket has to be modified to maintain proper contact (8-core machines only). Failing that the fans will roar up to full speed, some 5,200rpm – a welcome failsafe, maybe, but not one you want to hear all day.

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