Did you look up the average temperatures you can expect from it with that processor? If so, what are other people getting?
BTW, there are no guarantees that it is even supposed to be better than the stock fan. It probably is supposed to be better, but the stock fan/heat sink isn't as bad as many people think, especially if it is mounted right.
Which brings me to my next question: Are you sure its mounted right and are you sure the paste is being applied right? Anything even slightly off in there can make your temperatures horrible, especially air pockets in the paste.
Also, are you OCing at all?
BTW, just so you can be aware of this, heat comes from wattage pretty much. The FX-4100 is already a super high wattage chip stock and wattage scales up faster than performance when OCing.
Lastly, even 61c is not that bad and there is nothing stopping you from putting the stock fan back on there.