A big Maybe, if they will work together, there's no way of knowing how or at what freq without knowing the mobo and CPU....most mobos out there default DRAM to 1066 or 1333, so if you mix the sets and they run it will prob be at one or the other. To run 1600 or try 1866 will require manual setup. Any time you mix sets, even the same exact model, it can be and often is problematic