New (Old) overclock machine

Hey guys, been a bit since I posted on here. I'm looking to build a PC that I can overclock to the max. Probably a phenomc or something. I already have a new Desktop I built but I really want to build a desktop with a phenom for some reason. Which CPU will overclock better? Phenom x6 black or Phenom x4 black? More than likely I will be hunting for these parts used since they are fairly old. If you have any of these parts please let me know. I already have a gtx 970 I'll be using in this build. Would ideally like to get 5ghz more or less. This is all for fun and will probably be used as a storage/media library machine or forgotten about once I have a few months of fun with it. Thanks for any and all replies. -Blue

Are you after pure clock speed or overall highest performance?

Some of the X4's are a bit easier to get over the 4 GHz range than the X6es.

Yes and yes. Both preferably.