I really think that the PC8000's and the PC6400 are the exact same. I've got a pair of both 8000's and 6400's 512mb sticks in right now but need to test each kit individually. The SPD settings for both the 8000's and the 6400's are the exact same. That means that the 6400's have the 1000mhz EEP profile, which the 8000's obviously have also.