If you want to spend a half hour, and you are handy with a soldering iron, replace just the fan. Remember to get some screws for the new fan. You can splice into the new red and black wires and not have to solder it into the circuit board. Make sure it is the power supply fan because some computers have a case fan as well as the CPU cooling fans. Good luck.
P.S. There are some hefty voltages inside the power supply case so do not plug in the power supply while it is open.