Well, no idea what the problem is really. I did once have a CPU, or rather, my current CPU did once sound like a vacuum cleaner. I managed to solve it through the BIOS and SpeedFan.
So you could try, either getting an app like SpeedFan. Not sure if it'll be able to control the speed of the GFX card fan, but ought to be, and then lower the speed of it. While making sure the temperature don't go off the charts ofc
Or else, not really a quickfix though, but, you could try killing the fan and then putting a new, bigger and more silent one on top of the card. Might work :p