Some of the cheaper video card manufacturers love putting fans that can look fans but are horrendously noisy, I hoovered some dust off my Inno3D Tornado MX440 fan.....(with a low power dustbuster type thing, didn't actually touch the fan) and for a while it was horrendous.....is quite now though.
I have seen Geforce2 MX (Original) cards run without any kind of cooling at all, things get quite warm but no lockups occur, their GPU is running at 175mhz....I would say with the 200mhz GPU of the GTS you might need some passive heatsink cooling, does it have much of a heatsink under the fan?
Corm