My Galaxy Nvidia GeForce 9600 GT low power low profile card recently developed a very annoying whirring sound. I downloaded the Xtreme Tuner from Galaxy, which allows you to monitor temperature and manually change fan speed, and ran the fan at different speeds. Anything above 20% made the noise and at 100% it was really loud. I dismantled the card, cleaned the fan, oiled it, all to no avail.
I looked for fans online but I couldn't find one that matched and I didn't want to buy a VGA cooler. So, I dug around in my old parts bin and found a fan from an Xbox that had a similar 3 pin plug (looks like a standard CPU fan). Well, I hooked it up and voila, It worked! I ran the software and the temp was good (+- 50 C idle, +-75 C after gaming) and I was still able to control fan speed. I simply velcro'd it on to the video card, and after clipping one of the tabs off the assembly it fit in my low profile Dell C521.
It is just as quiet again and didn't cost me anything! Hoping this will help anyone with a loud VGA fan.
By the way, when I reassembled the card, I used Dynex Silver Thermal Compound and the idle temp dropped about 10 degrees C.