Help the AMD noob, this will be running 24/7 and probably overclocked of course.

AMD Athlon II X4 620 Propus 2.6GHz

AMD Phenom 9850 2.5GHz

AMD Athlon II X3 440 Rana 3.0GHz

All seem close in price, witch one will perform best running SMP

Hate to pick a dud for my first AMD set.