The 'exotic' cooling of the GeForce FX, called Flow FX, is supposedly quite noisy (audible above a quite noisy PC), which nVidia have promised to rectify when the card is finally released...

The demo board, which NVIDIA demonstrated in an nForce2 system, produced a lot of heat. The air coming out of the fan grille is hot to the touch. While the system was quite loud overall, we could still make out the Flow FX fan - not a very positive trait. NVIDIA has promised to refine the design to make it quieter.
From Tom's Hardware Guide

If your interested, I'd recommend you read the whole article on THG, as its quite good and also shows some more images like the one that Higher Talshiar posted.