It seems that there is a mechanical problem with the fan. The video card needs to be pulled out, and the fan removed. This is something you can do yourself.
Usually, there is a plastic or rubber cap on the bottom of the fan, where you can find the impeller's axis. Sometimes it's just a hole and you can directly see the axis. There is a small safety washer, usually white and made of Teflon. You can use a lot of tools and stuff to release this washer. It is completely cut on one side and you can see this cut when you push on it with something. What I usually do is I grab a couple of sharp thin things (needles, toothpicks, cutter, knife, paper clips, anything thin and strong enough), and push it from one side. This is not enough to remove it, but it should either pop one end out and then you slowly work it's way out with the other tool towards the other end, or it will slide a bit away from the axis, and then you can stick the second tool between it and the axis and pop it out.
After this you should be able to remove the impeller, by slowly dragging it out by the central knob, where the blades attach. It could oppose a bit, as the magnet passes along the metal part of the coil. Watch out for the other 2 or 3 stuff that might be on the axis, one or two rubber washers, ball bearings, maybe a little spring, make sure you keep them all and prevent them from falling on the floor so you can find them later when you reassemble the thing. :haha:
Try cleaning the small tube where the axis goes and the axis itself (I recommend alcohol), also rub the washers, spring, bearings & safety washer with a little piece of cloth sprayed with alcohol. Some dirt will come off. Clean up the other parts as well, the impeller & it's blades, the fan etc.
Then you can use either fine mechanics oil or a very little bit of petroleum jelly. I used both with success. Reassemble everything and it should be spinning OK now.