Yes, Rivatuner allows you to change the fan settings.
You can set the minimum fan speed, max fan speed, what temperatures the fan kicks in at.
I used it with my 8800GT before I put an Accellero S1 on it, but I cannot remember exactly how to do it. I read a tutorial on some other forum and it worked good.
Edit* Ok, I found how to do this on the GT200 series. Now my GTX 260 runs 40% idle up to 65C then the fan slowly rises with the temp up to 70%.
I used this guide: http://www.vaguetech.com/index.php?pageid=rt207
Along with the Excel spreadsheet in this post: http://forums.guru3d.com/showpost.ph...3&postcount=60
to calculate what my values should be
IMO, the guide makes it more complicated than it has to be.
If you have questions, I MAY be able to help.
The biggest problem with the default fan programming, is the Trange is too high so while the fan does speed up as it gets hotter, it doesn't by more than 8% I have noticed, where now my fan jumps 30% under load.