AMD's 12-core "Magny-Cours" Opteron 6174 vs. Intel's 6-core Xeon
 

If the Westmere Xeon EP were a car engine, it would've been made by Porsche. With "only" six cores, each core in the new Xeon offers almost twice the performance of the competition. A 32nm CPU that only occupies 248 mm2 the Westmere Xeon EP embodies pure refinement and intelligent performance, both Porsche traits. It's just made in Portland, not Zuffenhausen.

AMD's offering today is very different. Magny-cours is the CPU version of the American muscle car. It's a brutally large 12-core CPU: two dies, each measuring 346mm2 connected by a massive 24 link Hyper Transport pipe. AMD's Magny-cours Opteron has almost two billion transistors and 19.6MB of cache on-die.

http://it.anandtech.com/IT/showdoc.aspx?i=3784