My gaming rig originally had 1GB of matched Corsair PC5400 XMS in it. I play WoW and needed more RAM due to severe chop in the game, so I could and additional 2GB of Corsair PC6400C4 XMS memory. My question is, will I lose performance running both 5400 and 6400 together, or should I dump the 5400 and just run the 2GB of 6400? I have no other machine to stick the 5400 in. I also ran 3D Mark 2005 both with all 3GB in and with only the 2GB of 6400 and had no noticeable performance difference on the score. What do you think? Thank you for your feedback.