I killed my HD3870 by changing cooler : I want to know how.

Discussion in 'Mac Pro' started by haroldch, Sep 14, 2008.

  1. haroldch macrumors newbie

    Feb 15, 2008
    Hi guys,

    Yesterday I swaped the stock cooler of my radeon HD3870 for a zalman vf1000.
    Since then, the GC doesn't work anymore (even with the stock fan back)
    So after a night of check, test and prettty much everything, I'm pretty sure my GC is dead.

    What I want to know is what did I do wrong ?
    Do you think it could be a short circuit ?
    I'm a good mac user and I already did that on others cards (X1900 with an accelero for example.)
    I talked with xlryourmac and he can't see.
    I really want to find out a plausible explanation, because I'll probably buy another GC et wouldn't want to do the same mistake twice...(I know I'm crazy)

    so if someone really good at this can help...

    I have a Macpro clovertown 2x3 Ghz - 12Gb Ram- Raptor Boot- Raid 3To- Multibridge Pro 2

  2. Lord Zedd macrumors 6502a

    Lord Zedd

    Oct 24, 2007
    Denver, Colorado
    Probably nicked off a resistor, cracked the GPU, broke a solder joint or fried it with a small static shock.
  3. tobyg macrumors 6502a

    Aug 31, 2004
    My guess is the cooler didn't sit flush on the gpu. When you took the cooler back off, did it look like the heat sink compound stuck to the heat sink covered the entire chip? If it didn't, it probably didn't sit flush. Way back in the day I did that to an AMD CPU, it didn't sit flush and the CPU burnt and cracked the instant I turned the computer on.
  4. kalex macrumors 65816

    Oct 1, 2007
    could be short circuit or like others said, make sure heatsync is flushed against the GPU, u might need to put epoxy on it just to make sure it conducts heat to heatsync
  5. tobyg macrumors 6502a

    Aug 31, 2004
    I wouldn't suggest using any sort of epoxy in this case. I would not want to glue my GPU to my heat sink, makes it impossible to take the heat sink off again. And from what I've seen is not recommended in applications such as this.
  6. kalex macrumors 65816

    Oct 1, 2007
    Epoxy is not glue. its a heat conductor. what it does is creates a connection between chip and heatsync. heat dissipates when there is contact. if heatsync is not attached properly or has space between GPU and heatsync will not work correctly. Every CPU has it and I'm sure that GPUs also have it applied in some shape or form
  7. bartelby macrumors Core


    Jun 16, 2004
    Epoxy is a thermosetting polymer. I'm not sure of it's thermal conductivity though. But I'm sure it's not great.

    Thermal paste is what helps conduct the heat of a chip to a heatsink.

    Try Aralditing your processor to a heatsink and see how far you get.
  8. robbieduncan Moderator emeritus


    Jul 24, 2002
    You can get special thermal conducting epoxy for sticking heatsinks to stuff. I used to do it back in my younger PC modding days to stick heatsinks to RAM and chips on PCI cards.

    Edit: this stuff :)
  9. bartelby macrumors Core


    Jun 16, 2004
    Well, fine. I was wrong:eek:

    I probably should have googled thermal epoxy before opening my big gob...
  10. nanofrog macrumors G4

    May 6, 2008
    I've never seen it in that small a quantity before. Nice find. Thanks. :)

    Given the OP's need to attach the GPU cooler though, I wouldn't use it. Much easier to replace using paste and a mounting bracket. I'm not sure they would honor the warranty if the 3rd party cooler was epoxied on. :confused:

    Out of warranty, may be another story. :D :p
  11. haroldch thread starter macrumors newbie

    Feb 15, 2008
    Well thanks all of you...

    I'm not sure about epoxy. To join solders it's a good idea but not for chips I think.

    I used thermal paste as usual.
  12. kalex macrumors 65816

    Oct 1, 2007
    Sorry everyone. that's what i mean to say was thermal paste (which is also epoxy i think :) )

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