After trying a few different models (Galaxy 470, EVGA 470, Gigabyte 460) of video cards in the nVidia 400 series, I settled on two EVGA 460's in SLI because the other ones I tried were either too loud for my taste, or had other issues. The EVGA GTX (core 720/mem. 1800) 1gb is the quietest 460 card in my opinion. About on par with the Gigabyte card. Unfortunately the Gigabyte cards have a different problem. I bought two of them to use in SLI, and since they don't exhaust heat from the case very well, the card in the lower pci-e slot was basically cooking the top card and causing the top one to overheat and shut off constantly while gaming. Definitely stay away from the Gigabyte cards if you want to run SLI, unless your case has very good ventilation.
Anyways, the default lowest fan speed for the EVGA cards is 30% (or 40% if you have the one with an older bios). At this level of fan speed, the cards are still the loudest component in my computer. I don't care about noise while gaming, but I really hate any noise coming from my case while browsing the web or doing work. So, I took it upon myself to see if I could somehow make the GTX 460s even quieter at idle/2d mode than they already were. After searching for information, it seemed the only way to make the fan any quieter would be to reduce the minimum fan speed through a bios mod. Unfortunately, the only method I could find for doing this was with nVidia Bios Editor made by orbmu2k. Too bad he doesn't freely release this program, so the only way to make use of it is to get someone else on another forum who has the program to mod your bios for you. Also, NiBiTor doesn't have this option yet either. I figured there must be another way.
After comparing bioses available on different forums I figured out how to mod the bios for fan speed with a quick HEX edit. The purpose of my post is to share this information with other people so they can do the mod too, and possibly have a quieter and cooler running card(s) while in 2d mode.
Programs you'll need: a good HEX editor (I recommend UltraEdit v14+), NiBiTor v5.8+ (to create checksum and lower voltages), and nvflash 5.95+ (to save bios and flash your modded bios)
1. Use nvflash to save your bios. I won't go into too much detail in this step because a good tutorial for using nvflash is located here: http://forums.nvidia.com/index.php?showtopic=141631
2. Note: this tutorial is a bit outdated. You do NOT need to create bootable media IF you are using the newest version of nvflash because it does support flashing in 64-bit Windows.
3. Make another copy of your saved bios. One will be for modding, and the other will be useful if something goes wrong.
4. Open up your bios in a HEX editor.
5. Go to line 6600, column f (see picture).
6. If you bios has '1E' at this location it means your min. fan speed is locked at 30%. '28' in hex would mean its 40%. (These are just straight HEX -> DEC conversions).
7. Change '1E' to '14' for 20% fan speed. I don't recommend going below 20% because the pwm fan on the card may not start up at such a low speed, but you can always try if you're brave...
8. Save your edit, and then open the bios in NibiTor.
9. Navigate to Tools -> Fermi Voltage.
10. Change 'Setting 0: 0, and 1' to some lower value (see picture).
11. I used 0.7 volts on my cards, and they work fine. This voltage may or may not work for your cards so it might be best to change this in a step-wise way (i.e. try lower V, flash, test, etc.)
12. 0.6 V is probably the lowest possible setting without having issues, but I haven't tested it so I can't say for sure.
13. Save your modded bios.
14. Disable SLI if you have it on.
15. Use nvflash to flash your modded bios (see tutorial link in step 1.).
So far this mod has been working out quite well for me. My cards are noticeably quieter and produce slightly less heat in 2d mode. Since it is a pwm fan on these cards, they rarely idle at 20% fan speed. It's more like 22%-25%, but that's still good. I hope this mod helps people, but if it doesn't and something goes wrong, I take no responsibility what-so-ever. Use this information at your own risk, and know how to flash back your original bios in case something goes wrong. This procedure should work with other gtx 460 models/brands, but I haven't tested it personally so I can't say for sure.