MOD YOUR RADEON HD 6900 GPU'S COOLING

We have had the opportunity to evaluate a number of AMD Radeon HD 6900 series cards since their release. For the most part, the cards have been well-built and stellar overall performers. A small num­ber, however, have suffered from minor cooling-related issues that can have an adverse effect on GPU temperatures. The issues have never caused any instability or major problems to speak of, but reme­dying them will lower operating tempera­tures, which in turn can result in a quieter, more overclockable card.
On the backside of reference Radeon HD 6900 series cards, there is a metal re­tention/spring plate that secures the GPU heatsink in place and applies constant pressure to ensure good contact with the chip. On occasion, that spring plate hasn't been fully tightened or was slightly bent to the point where it wasn't applying optimal pressure. While disassembling cards to fix the issue, we've also found that some Radeon HD 6900 series cards have had way too much thermal paste applied to their GPUs. Ideally, only a small amount of thermal interface material should be used to facilitate heat transfer from a chip to a heatsink; a paper-thin amount is all that is necessary. But on many of the Radeons we've disassembled, there has been so much thermal paste installed that more has oozed out from the sides of the GPU die than is actually necessary in the first place. And having too much thermal paste applied to a chip can actually hinder cooling performance.
To ensure that an affected Radeon HD 6900 series card is optimally cooled by the stock heatsink, there are a few steps you need to take.
1 DISASSEMBLE THE CARD To disas­semble a reference Radeon HD 6900 series card, first remove all of the
screws on the backside of the PCB that hold the rear stiffening plate in place, and then remove the plate. Then remove the two screws at the top of the case bracket above the MiniDP ports. Next, remove the four screws holding the heat­sink's spring plate in place (image A). At this point, gently rock the entire cooler assembly and pull it away from the PCB, being careful not to yank the wires for the fan out of their connector. Once the cooler is loose, unplug the fan connector and set the cooler aside. Be careful not to remove any of the sticky thermal pads on the memory chips.
RE-APPLY THERMAL PASTE With the card disassembled, you'll want to clean off the old thermal paste (image BJ. Use some isopropyl alcohol (or other cleaner safe for electronic circuits] to carefully clean all of the stock thermal paste from the GPU and heatsink's base. Then apply a very thin layer of quality thermal paste to the GPU; the smallest amount necessary to cover the chip is all that should be used.

RE-ATTACH AND ADEQUATELY TIGHTEN SPRING PLATE

Now the cooler can be rein­stalled, but before re-attaching the spring plate make sure it is not bent or deformed in anyway, and add a few thin shims to raise it slightly from the PCB and increase the spring pres­sure. Keep the shims very thin so as not to damage the GPU —we cut up an old rewards card from the supermar­ket. Stick the shims to the rubber pads on the underside of the spring plate (image C) and then put it in place and tighten the screws in a crisscross pat­tern. Then reinstall the backplate and you're ready to test.
The cooling on our project card was definitely improved. Before touching it, the GPU on our 6970 idled at 44 C and peaked at about 82 C. After the mod, the GPU's idle temp remained steady at 41 C. Peak temps still hit 82 C because the cooler is throttled based onload.butittook somewhat longer to hit the peak, and the card seemed to cool down faster, too.

MOD YOUR RADEON HD