You can start the OC with stock cooling. Just push it up a little, then when you get an after-market HSF, you can get farther
[FREE BUMP]
The 720 can usually do like 3.4ghz on stock voltage, and typically anything on stock voltage the stock HSF can handle. Thats over 20% overclock. Even if you can only get 3.2ghz, thats still close to 15%, and I KNOW you can get 3.2ghz on stock voltage.
You want a Xigmatek Dark Knight?
I have a xigmatek S1283 here you can have for free, just whatever the cost of shipping, will come fanless and without the rubber fan clips though... and the base finish leaves a little to be desierd. (I used zip ties personally with it and ran two slipstreams in push/pull which is why i dont have the fan clip/holders, and the base finish has four blemishes in it due to the highly concave IHS that was on my Q9450 until i lapped it.