For overclocking, nothing beats a single-core Opteron, except for an E6300 or E6400. If you end up with a bad stepping, 2.5Ghz could be all you end up with, if you go with an Opty 170. The 152 is guaranteed to do 2.6 Ghz, and nearly every one of them should do 3.0. Of course, paying that much for a single-core processor isn't what I would recommend, but it is your money.