They might play, they might might not, even if you get another stick of the same exact model. If they do play, it will depend on the mobo/CPU what they can/will run at, if the mobo is native to 1066, then they will prob go to the mobos default, again IF they will play, it's possible to can set them to run at 1600 manually....Lots of variables, but the big one they may not even play together. It's best to get all you want/need in a single package, that way you get sticks tested to play nice