I don't know specifically about the paste on the FX series of cards, but it's general knowledge that vid card companies don't use a quality paste, plus a lot of times it's not even well-spread. I got an extra 15MHz on my Ti4200's core by using some leftover OCZ silver paste, making sure it had 100% coverage as the 4200 had only about 40% coverage from the factory with cheap paste...
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