An unlocked phenom II x2 560 would perform the same as a phenom IIx4 at 3.3GHz , since it is just an x4 with 2 cores disabled: http://www.anandtech.com/bench/Product/88?vs=187
^since AMD does not sell quad cores at 3.3GHz, here is the next best thing, 3.2GHz. little difference.
Do not forget that amd locks their cores for a reason, they are often defective. The only reason it sometimes works is because of market demand: amd will be forced to disable 2 cores on a perfectly good quad core and sell it as a dual core to meet the market demand.