cant remember if i made a thread but anyways...yah in the thermalpaste a glue or a thermalpaste type . like will it be sticky? i have a radeon 7000 and it uses the glue stuff.
I think it does void the warranty, but its cool if you know what your doing...
Just make sure your card is working 100% fine before you make any changes to it. Stress test it and so on to make sure its working A ok.