The 80mm fan will overflow over the HS and blow air under the socket, and make your temps even more drastic of a change on AMD boards due that temp probe is under the socket. Now with the cool air flowin under there cause of the oversized fan is just gonna throw off your temps and really not fair to compare between your previous 60mm setup. But its also nice blowin that stagnet hot air under the socket, reducing temps even more.
But in all this is a great mod, in all my comps i've been running PCP&C 80 Silencers fans ontop of my HeatSinks, GW FDP32, GW FKP, Alpha PEP66, Hedgehog. Its impossible getting a fair amount of air and quietness with a 60mm fan.