Chris, London, UK, Asus Laptop Heatsink
I upgraded my laptop (Asus C90S) from a nVidia graphics card (which used to overheat – 80 degrees) to an ATI mobility graphics card
The heatsink wouldn’t touch the GPU so I needed the copper shim to pad out the gap.
The 0.5mm copper shim covers the GPU, I used heat transfer grease on both sides. The aluminium heatsink then bolts on to the card
I tried different pads but anything thicker would raise the heatsink too high away from the RAM chips. And with a thermal pad it was running at about 64 degrees.
This was a successful upgrade as the new graphics card is now running at around 58 degrees. The copper shim transfers heat better than a thermal pad.