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b06tmm

macrumors regular
Original poster
Jul 23, 2009
242
25
South Louisiana
Hi All,

I'm working on a friend's 2009 24" iMac (A1225). For a while now the computer has been shutting down when playing flash videos and just got to the point of not booting unless you pull power first and just generally acting quirky.

Other than being disgustingly filthy (clogged fans, etc.) I found the heatsink for the on-board Nvidia chip loose, all of the pins were broken.

Does anyone know what these things are called and maybe somewhere to source them?

E9dTNEl.jpg


72DBzYG.jpg


Barring finding them, does anyone have any ideas on what I can use to do the same thing?
 

cynics

macrumors G4
Jan 8, 2012
11,959
2,155
Those pins go through the board and clipped on the other side correct?

If that is the case I've used metal screws with similar widths and length with matching nuts and hard nylon washers to isolate and insulate them from the logic board.

Push the screws in compressing the springs a little over half, hand tighten the nuts and release.

If there is room available use a backup nut on the screw so it can't work loose. If not dry fit it, see where the nut will stop and mar the threads of the screw at that point. Then you'll need to use tools but tighten the nut over the marred threads so its tight.

I've also used plastic and nylon screws/nuts in the past but I've found the constant pressure from the spring combined with heat cycles of the device cause them to eventually fail albeit it took 2 years on and it was on a piece of machinery that had vibrated a lot. Metal screws fixed it.

Just be careful to there is no chance of the metal touching anything conductive on the board or on other components when reinstalled.
 
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b06tmm

macrumors regular
Original poster
Jul 23, 2009
242
25
South Louisiana
Those pins go through the board and clipped on the other side correct?

If that is the case I've used metal screws with similar widths and length with matching nuts and hard nylon washers to isolate and insulate them from the logic board.

Push the screws in compressing the springs a little over half, hand tighten the nuts and release.

If there is room available use a backup nut on the screw so it can't work loose. If not dry fit it, see where the nut will stop and mar the threads of the screw at that point. Then you'll need to use tools but tighten the nut over the marred threads so its tight.

I've also used plastic and nylon screws/nuts in the past but I've found the constant pressure from the spring combined with heat cycles of the device cause them to eventually fail albeit it took 2 years on and it was on a piece of machinery that had vibrated a lot. Metal screws fixed it.

Just be careful to there is no chance of the metal touching anything conductive on the board or on other components when reinstalled.

Thanks for your reply, it's appreciated.

What I ended up doing after applying some some thermal compound to the internal GPU was to use some small zip ties.

dzNLpGB.jpg


FUPEwWh.jpg


I then used some other zip ties to cinch the heatsink down.

It may not be the optimal solution, but it works for now.
 

cynics

macrumors G4
Jan 8, 2012
11,959
2,155
Thanks for your reply, it's appreciated.

What I ended up doing after applying some some thermal compound to the internal GPU was to use some small zip ties.

dzNLpGB.jpg


FUPEwWh.jpg


I then used some other zip ties to cinch the heatsink down.

It may not be the optimal solution, but it works for now.

In all likelihood that will be perfectly fine however I've seen zip ties become brittle with heat and time. Just make sure the springs stay on there because the zip ties will expand and contract with thermal cycles.

Which thermal compound did you use? While any will work after using Kryonaut Thermal Grizzly (I believe thats the name) on a laptop I found very good results.
 
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