Quote Originally Posted by BeepBeep2 View Post
General rule of thumb Phenom II is pretty close to Core 2 CPC, maybe 5-10% faster in some things.

When you have a quad core Phenom II CPU stock at 3.6 Ghz it will pretty much blow a stock Q9550 out of the water...as for the six cores they are up there with Intel Core i7 9x0's most of the time.
Actually Core 2 (45nm) is generally slightly faster than Phenom II per clock:
http://www.anandtech.com/bench/Product/81?vs=50

Most Q9550s can do 3.8 - 4.0GHz on air, so you need an X6 to really see a noticeable difference, and then only in highly threaded apps. An X4 would be a slight downgrade.