You don't add them together. It's like putting four cars together than can go 100 MPH each. They can't go 400MPH just because they are all linked together, but they can carry 4x the cargo (data in this matter.) Even AMD fanboys like me will tell you, if you want to OC, go Intel. 775 is an Intel pin configuration, which won't work with AMD CPU's. If you want to run the Phenom you need AM2/AM2+.
P.S. Also, if you want to OC an AMD, look for the Black Edition CPU's.
You hire 4 truckers with trucks to drive the speed limit and get the same payload there with out doubling back on trips and returning each time. Because of road LAWS(watch this word) you cannot exceed a set speed limit.) In CPUs, you cannot exceed Moore's Law, which basically states that eventually CPUs will head a brick wall in which there freq. cannot go any higher, but you can still just put more CPU cores in one die and get around the same effect you would be achieving by rising above Moore's Law.