I went through Dell's website for memory upgrades and based on Dell's and also Crucial's update advisor I purchased 4 x 1gb PC2-6400. I noticed that my memory isn't running full speed though, it says 667mhz in the BIOS. I updated the BIOS hoping that it would solve the issue but it hasn't. Why is it not running at the right speed? How can I fix this? If this pc can't handle the speed why is it on both update sites? I hope I didn't waste my money. I was running PC2-5300 and the upgrade advisor recommended this ram upgrade.