True; that the Cooler Master Hyper 212 will give the best cost ratio.
But I like getting the voltage regulators cooled too when running so much voltage (assuming you intend to OC the 955). I suggest the Scythe Big Shuriken, a highly rated cooler for only $5 more, that will cool the CPU very effectively, as well as the ram and other components nearby.
Keeps my 4.07ghz 955BE at 27c idle and 51c under full load (8 hrs of prime95), also comes with 2 high cfm fans for push/pull. Newegg has some for open box special right now at <40 ea. =]