Q: Thermal Pad Thickness, Brand and Type of GPU Memory (Surrounds the GPU Chip) of Late 2009 iMac?
Hi. I will be repairing (and cleaning after 6 years) the late 2009 iMac coz' the screen has five 2cm thick, evenly distributed, striped vertical lines (it is still useable in Safe Mode) which indicates a good GPU chip (used to pass all stress tests for GPU and GPU memory) but a subcomponent surrounding it has solder joint fracture coz' it may have overheated during summer (which was a record high, 36 to 42 Celsius) and OS X may have not revved up the fans enough which may have helped cause the solder joint fracture.
When I open the iMac on monday, the thermal pads for the GPU's memories (surrounds the GPU chip which I'm gonna use a thermal paste with) may not be in good condition anymore. I was wondering what thickness should the pad be for this iMac's GPU (an ATI Radeon HD 4850 512MB ), what brand and what type (though the thickness may be the most important)?
Thank you. God bless. Rev. 21:4
iMac, OS X El Capitan (10.11.1), iMac Late 2009
Posted on Jul 16, 2016 5:49 AM
Hi. The 3M thermal pad (I may have wanted the Gelid brand more may be on par with Gelid's best performing thermal compund) seller I bought from says it's 1.5mm (from Ati hd4200 series up to 5 series), though when I tested the gaps between the ram chips and the other chips (that are not GPU) that was covered with thermal compound, 0.5mm already wouldn't slip through the chip with the widest gap (measured the by folding strips of paper and by using a digital caliper to measure the folded paper); but seller knows best- I'll go with 1.5mm. It may need 3 times my calculation for the chips to get a good pressure, I guess, coz' the vram and other chips don't have the spring loaded clamp that the GPU has.
God bless. Matt. 16:18
Posted on Jul 22, 2016 10:38 AM