So I bought this card from someone that doesn't want it anymore. My "ATi/AMD Radehon HD 4870 1GB" have broken. This is my 2nd AMD 48X0 card that failed on me in a row, so I went over to the nVIDIA side. Although this is not an upgrade, but rather a replacement I decided to overclock. I was surprised to see that on the 1st attempt I could overclock the core to 1Ghz and run the shader clock @ 2.0Ghz with Furmark running stable for 10-minutes. However I removed the EVGA cooler to see if I can modify my ThermalRight TRAD2 cooler somehow to fit on this card and I noticed sometihng VERY VERY disturbuing when I removed the thermal paste. If you press the cooler to the card (the original cooler, not the TRAD2) and you hold it up against the light you will notice that the cooler NEVER touches or even makes contact with the GPU in the center. This is not the cooler that is bent, I've placed a small piece of glass on the GPU's heat spreader and I came to the conclusion that the heat spreader on the GPU is not perfectly flat - it looks as if it could be a manufacturer issue and that the heat spreader is a little bit bent. This is not good. Has anyone ever heard of this or maybe know what I can do about this? This will of course affect the efficiency of any aftermarket or even the stock cooler. What thermal paste is the best that I can use or how can I close this air gap (it's quite big)?
Personally I would use Artic Silver Compound. One more thing you maybe could do is, use an MiniDrill or some tool like that with an grinding grinding wheel and grind the heater down a bit where it would not need to touch the GPU! I had done that a few years ago even on an EVGA Card which had the same problem. That just worked well for. And I also placed an 2. cooling fan on the other side of the PCB above the place of GPU. Since that card just works very well for now more than 3 years!
Er....! Now I understand what you were mean with Heat-Spreader!! I never had done that with an GPU, done with an older AMD Athlon CPU which were getting very hot. I also was using from an even older AMD CPU an kind copper frame which were slightly (0.2mm) more thin than the distance of top of CPU chip at the middle and the PCBThat was working well and I was getting the temperature down by nearly 20°Celsius. May that would work the same way for the GPU. And I ,use all time Artic Silver as heat compound, which isn't cheap by the way! I wish you good luck and be very careful!!