G4 Powerbook Ti - Thermal paste

Discussion in 'PowerPC Macs' started by CooperBox, Dec 20, 2015.

  1. CooperBox macrumors 6502a

    CooperBox

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    France - between Ricard & Absinthe
    #1
    Regarding thermal paste on a G4 PowerBook Ti, I must confess that when I disassembled and re-built mine a short while ago (a 667MHz model) I didn't re-apply any thermal paste. The bottom of the computer gets pretty hot (it did that when new), fan comes on after a while, but has never had a thermal-controlled shut-down.
    I've just checked my disassembly photos and note what looks like 3 possible locations on the rather large and complex heat-sink, 1 with thermal paste and 2 with thermal pads. Would it be acceptable to apply thermal paste to all three locations?

    G4 Ti Heatsink 1.jpg

    G4 Ti Heatsink 2.jpg
     
  2. MacCubed macrumors 68000

    MacCubed

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    #2
    When I reassembled my 667, I just repasted the CPU
     
  3. CooperBox thread starter macrumors 6502a

    CooperBox

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    #3
    Thanks for this. I think I'll try the same, and measure some temps before/after.
     
  4. Altemose macrumors G3

    Altemose

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    #4
    Using thermal paste instead of a pad would lead to too large of a gap between the mating surfaces to effectively conduct heat.
     
  5. CooperBox thread starter macrumors 6502a

    CooperBox

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    #5
    Interesting comment which had in fact crossed my mind.
    On the spare heat-sink shown above, I have just measured the thickness of the two white thermal pads (top photo). Both are 0.015"
    When I next disassemble my PowerBook, if I find there are no thermal pads attached, I'll use the spare heat-sink (pads look good and not particularly crushed) and just use thermal paste on the single metal pad location.
    Personally I can't see any advantage in adding thermal paste on top of pads, unless anyone has experience and comments in this respect.
     
  6. CooperBox thread starter macrumors 6502a

    CooperBox

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    #6
    I've just been reading that thermal pads are often included on the bottom of heatsinks as they are cleaner and generally easier to install. They do however conduct heat less effectively than a minimal amount of thermal grease.
    This gets me thinking that in the PowerBook Ti assemblies, these pre-installed pads, in addition to their prime role to conduct heat, could well have been a precious aid in the production cycle, i.e. to speed-up assembly.
    If speed of assembly is not a criteria (by us keen MacUsers), perhaps an application of thermal grease (in lieu of pads) may be an advantage. I'd have to do a few detailed height measurements of the three metallic-base locations to understand if my theory makes engineering sense.
     
  7. Altemose macrumors G3

    Altemose

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    #7
    @CooperBox On my 1.67 GHz PowerBook G4 15" SLSD, I replaced all of the pads and paste with a good layer of Arctic Silver Ceramique 2. It has worked great but I must warn against using a "thin" paste where there was a pad. If you use a thicker paste by nature, like Ceramique 2 then it should work great. Keep in mind that the Aluminum PowerBooks may have different tolerances in the mating surfaces, so while it may work great on my machine it may cause a Titanium PowerBook to overheat.
     
  8. flyrod macrumors 6502

    flyrod

    Joined:
    Jan 12, 2015
    #8
    My 12" powerbook had a pad on the GPU (which tended to run quite hot). I replaced it with a copper shim of the same thickness and some thermal grease. This significantly reduced the GPU temperatures reported. It did raise the CPU temperatures when running GPU intensive things, which I attribute to the entire heatsink assembly carrying heat from the GPU. But overall the machine runs cooler and the fan comes on less.
     
  9. JRDN macrumors member

    JRDN

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    Oct 24, 2015
    #9
    I used some K5 Pro that I got when fixing up an iMac. Just balled some up and put it over the GPU and other thermal pad spots. Also replaced the thermal paste with MX-4 on the processor. Runs nicely now.

    Unfortunately the TiBook doesn't have any thermal sensors so I used a heat gun to check temps under the keyboard. ~45 C running OpenMark
     
  10. CooperBox thread starter macrumors 6502a

    CooperBox

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    #10
    K5 Pro looks an interesting product. Reading between the lines it seems that it's a paste that needs to be reasonably 'fresh' for best results, i.e. expiry date should be heeded. In other words once opened, to use within a reasonable time. Sounds good for those with plenty of computer refurbishment activity, but would be in very occasional use by myself. But well worth bearing in mind.
     
  11. JRDN macrumors member

    JRDN

    Joined:
    Oct 24, 2015
    #11

    I wondered about this as well.

    This was brought up on Amazon and the makers responded with:

    So if I don't open and use the stuff, it will automatically expire in 30 months? I'm confused with the expiry date thing...
    Answer:
    K5 PRO pro doesn't actually expire. We need to have an expiration date in order to follow EU regulations.
    By Computer-Systems on March 11, 2015
     

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