My PC6400 G.Skill F2-6400CL5D-4GBPQ will do 485 or 490/DDR 980ish @ 2.0v. My set of PC8000 F2-8000CL5D-4GBPQ will do at least 530/1060 DDR, but I haven't seen how far I can push it yet. Notice that they are the same part number exactly, except for the speed rating. I personally believe they have identical IC's, but don't know that for sure. It's very likely, though, because there are very few 2GB sticks with IC's that overclock well.