PowerBook 1.67 GPU Heatsink won't make contact with chip

Discussion in 'PowerPC Macs' started by burnout8488, Dec 23, 2011.

  1. burnout8488 macrumors 6502a

    Joined:
    May 8, 2011
    Location:
    Endwell, NY
    #1
    [​IMG]

    Last time I was in the PB a week ago I tightened down all of the logic board screws properly, all seemed snug and tight. I'm replacing the lower case today and this caught my eye. The GPU barely made any contact with the heatsink, only the thermal paste made contact. It appears only the peaks of the thermal paste "dotted" the heatsink without actually being pressed against it. The CPU is obviously being properly pressed against the heatsink.

    Do I need to add a few washers on the screws above the GPU to correct this? I'm surprised it was cooled at all, got lucky I guess, glad it was only a week like this. I don't want to bend the logic board outside of it allowable tolerance, is this a design flaw and perhaps the reason why Apple put GOBS of thermal paste on these chips from the factory?

    This is what it looked like before I went in last week and cleaned things up:

    [​IMG]

    :eek:
     
  2. OrangeSVTguy macrumors 601

    OrangeSVTguy

    Joined:
    Sep 16, 2007
    Location:
    Northeastern Ohio
    #2
    That second pic looks like an Apple OEM paste job :p
     
  3. burnout8488 thread starter macrumors 6502a

    Joined:
    May 8, 2011
    Location:
    Endwell, NY
    #3
    You would be correct! It turns out the GPU really does use a very thick layer of paste to make contact with the heatsink. Apple puts way too much on, so I redid everything and only left a thick "pad" of thermal grease on the chip itself and built it up a little so it would be squashed down. This way the excess doesn't splatter all over the entire chip. The CPU can make metal-to-metal contact with the heatsink, so I applied a normal dot of thermal paste to that.
     

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