Linux Nvidia drivers might also have the GPU fan speed issue

Just read a mail from Alberto Milone, where he mentions the warning issued by NVIDIA that the drivers 195.36.08 and 195.36.03 might be affected by the same GPU fan speed issues which were detected earlier in the windows drivers. You might not face any troubles with it but there have been a few reports so its better to be careful. The problem might take a while to resolve, so its better to take the measures suggested by Nvidia and Alberto Milone(for Ubuntu). Here I have discussed those measures.

According to Nvidia, until the problem is resolved, Linux users should revert to 190.53 web release or the 195.30 public beta. They are going to remove the 195.36.08 and 195.36.03 drivers from NVIDIA's FTP site.

Otherwise, you might want to disable the current suspicious driver, using either of the 2 methods suggested by Alberto Milone in Ubuntu. This might be the case for only Lucid users.

Disable the driver with Jockey

Go to System->Administration->Hardware drivers, disable the Nvidia driver and restart the computer.

Using following commands.

Open a terminal (Applications->Accessories->Terminal) and execute the following commands to temporary solve the issue.

[shredder12]$ sudo update-alternatives --config gl_conf (and select the alternative provided by mesa)
[shredder12]$ sudo ldconfig
[shredder12]$ sudo update-initramfs -u
[shredder12]$ sudo mv /etc/X11/xorg.conf /etc/X11/xorg.conf_old

Now, restart your computer.

Sources: http://www.nvnews.net/vbulletin/announcement.php?a=39
               http://albertomilone.com/wordpress/?p=482