Not sure how many people are actually affected by this problem, but I want to write this down for the sake of documentation, anyway.

If you have a dedicated crunching machine using linux, which is running one or more fermi cards for BOINC, you may have wanted to increase fan speed to achieve lower GPU temperatures. As the machine is dedicated, there is no need to have a screen attached to it, and thus there is no reason to run an X-Server on it, neither.

There are a few howtos out there that address the problem.
- Some are based on nv-control, a deprecated tool that does not support fermi cards. Just forget it.

- Newer posts usually mention nvidia-settings, which is a standard tool in the linux world. After modifying the xorg.conf, adding "CoolBits" "5" in the Device section, a new slider should appear in the nvidia-settings frontend. This seems to work for most people. Problem: nvidia-settings requires a screen attached to a running X-Server to work, which is pointless in a headless system and it gets complicated when you have more than one GPU.

- The solution for me was a script I found by accident: https://sites.google.com/site/akohlmey/random-hacks/nvidia-gpu-coolness. Apparently, it was developed for a business computer running a bunch of Tegra cards in a headless configuration. In short, during runtime the script identifies all the GPUs with their specific addresses. Then, for each of the GPUs an X-Server is started using a default xorg.conf, which simulates an attached screen. This way, for a moment nvidia-settings sees what it needs to allow a fan speed adjustment to this particular GPU, before the script terminates the X-Server again and moves on to the next GPU. So, when executing the script you will hear the fans of your cards spooling up one by one (which sounds pretty cool, by the way).

An installation is not necessary. Simply extract the files to a folder of your choice and adjust the path in the script file to point to this folder. The more sophisticated linux buffs out there will know how to include the script to the boot process, otherwise you will have to run it manually after each restart of your system.

Option "CustomEDID" is cool, I have missed one.

If you need nvidia controls, you always need xserver. If there is no monitor, you need at least "ConnectedMonitor" option. Then also remote desktop via vnc is working.

If you have two cards, you need to setup two xscreens or TwinView (for 2xx drivers). New 30x driver support multiple devices with one xscreen.