If you have an older Geforce 2 GTS or MX card that came with a fan on it, chances are the fan is dead by now. The sleeve bearing fans they typically ship on video cards do not last. What to do?
If you can replace just the fan and avoid removing the heatsink, do that. Unfortunately, many chip coolers are sold exactly as that, so buying only the fan as a replacement is impossible. And the chip cooler itself is rarely sold at a reasonable price considering the age of the video card. Otherwise, a solution with more longevity is passive cooling. You can buy a part number HS325-ND heatsink from Digi-Key.
Remove the existing chip cooler by CAREFULLY prying between the chip and heatsink on the side where there is the least amount of glue. You have to be careful here for two reasons. There are small surface mount components and traces on the circuit board that could be damaged if you are not careful. Also, the chip package itself has tiny traces that lead from the chip core to the BGA contact points. If even one of these is damaged, the card is ruined.
Use a medium grit sandpaper and sand off the thermal glue that remains on the chip. You don't have to get rid of all of it, but you do need to get rid of as much as possible so that the chip with sanded glue is as flat as possible. Here again, avoid accidentally sanding the BGA traces on the outer diameter of the chip.
Wipe the chip down and attach the heatsink using the provided thermal tape, or glue a new chip cooler onto it. If you go with the thermal tape or pad, it would be advisable to secure the heat sink with a zip tie or something similar, because the tape or sticky pad has about a 50/50 chance of letting go at some point, which will then lead to a fried GPU.
Monitor the chip temperature for a while to make sure the cooling solution is effective. On a GF2, I have no problems with normal desktop use with passive cooling.
Check those capacitors for bulging and/or leaking while you are at it!