Now be advised, if you do the following, you are doing so at your own risk! I will not be held liable and or responsible if something goes wrong!
I've done this twice for overly noisy CPU motors and fans and once for a noisy fan atop one of my old video cards.
Take a very lite amount of traditional "
3 in 1 oil, tilt the video card upside down, so the fan in pointing at the floor, with the eye dropper end of the oil dispenser, give the post that the fan is built on a couple lite drips of the oil. Then hold the video card upside down for about 2 to 3 more minutes, then carefully turn the card "right side up", as so the fan is pointing to the ceiling. Watch to make sure the oil now is using the fans post to slip down and get into the motor mechanism. After about 1 minute of the oil sinking into the fans motor and housing turn the card back "upside down", bust out a hair dryer, plug it in and set the fan to blow out a medium amount of cool air. Allow the hair dryer to blow air on the fans post and motor for about 2 to 3 minutes. Confirm there is no longer any active oils on the fan blades, the post and see if you can look where the post meets the motor, confirm there is no active oils there to. Once you feel certain that the oil in the exposed areas is now dry, plug the card back into it's slot inside the computer and "go for broke"!
It should work, it has for me in the past, quiets old and new fan motors and posts down to a gentle whisper.
Good luck....................."Remember, own risk"!