I have two fans running front and back and i think it is my heat sink that is making all the noise. But it is so loud that i cant fall asleep while my computer is on. Somebody please give some advice on what to do.
Get some quieter fans. Look up the dB rating when buying. Less than 26dB should do you well. Problem solved.
If you dont want to turn it off, or get quieter fans, get a fan controller. There are a wide wide range of different options, you just have to pick one thats right for you and your case. Problem solved.