I'm guessing your fan might be running at full speed since it is probably a 2 pin fan and it's usually the case on lower end cards.
You could always go fanless and find a better bigger heatsink though the card may still run a bit hot.
Or you can look for a different fan that will work with the 2 pin header on your graphics card and is less noisy. Unfortunately, I never really mess with changing the heatsink or fans on a lower end card since I always usually go for the better cards so I can't really say what is a good fan you can get to replace your existing fan. Speedfan which is a decent fan adjusting program may help though your fan is only a two pin fan so that might not work.