i read somewhere that nvidia tried so hard to make the chipsets work good with ati cards that they didnt make it good with their cards
that's pretty much true...don't know how it'll effect the 6600GT, but I know the nf3 chipset hinders the 6800GT that's for sure, nf2 and nf4 are great chipsets but then they fugged up with nf3..
a lot of people experienced random freezes in games, not permanent freeze like...the entire thing would freeze for 1-3 seconds then play fine again....seems to be something with the throughput.
My 6800GT clocked to 433/1185 on my nf2 and XP-M platform..I move it to nf3 and the chipset wont allow me to go further than 415/1120....
google up '6800 nf3 chipset' or something along those lines and you'll find tons of people with issues with it