I bought one because I was experiencing the same issue. You want this
which is actually under the M6N section.
Install is pretty easy,
1) open it up all the way to the CPU
2) remove the heatsink pipe
3) unplug the fan power connector
4) unscrew the first fan screw
5) the second fan screw is kinda inaccessible, but if you have the right screwdriver, you can get it angled in there and unscrew it
6) pop the new fan in
7) put everything back.