I this your card?
If you look at the first (top) picture and pass your mouse curser over it to enlarge, you will see, just under the fan fins, 4 tiny screws. Take a small screwdriver that is magnitized and back those screws out, and I suspect that the fan will come loose and can be removed. Most likely there is a tiny plug that you can detach to free it from the electrical feed wire. These fans are manufactured by 3rd party suppliers and are pretty well generic in size.
Now you have two options:
#1: Examine the fan; most of these are pretty generic. On one side (or maybe both, but not usually) there will be a small, round sticker over the center where the axle shaft end terminates. Peel that off, exposing the end of the shaft. Take a small drop of light machine oil ( 3 in 1 oil will work) and place it on that exposed end. Rotate the fan to let the oil penetrate, and leave it sit for 1/2 hour. Wipe the excess off and replace the small sticker/seal ( it is usually glued on). Sometimes the shaft has a bit of space where it is mounted into the body, then take a small dab of Lithium grease on your finger, and press firmly to work it in as far as you can. I fix noisy fans all the time that way.
#2: Now you can measure the fan diameter and the mounting holes, then look for replacements. Remember, all you really need are two holes to mount to. Four would be great, but two will work fine if that is all you can find. These fans are not under a lot of stress & vibration, and it really doesn't take much to anchor them.