It will not mess up your dual channel. Please note that channel does not equal DIMM, but refers to the way the memory controller sees things. Look here at the DIMM slots... slots 1 is on one channel, and slots 2 and 3 are on another. As long as the same amount of memory is stuck in each channel (and the specs are the same, of course), you can use dual channel. So... stick the smaller sticks in slots 2 and 3 and the big one in slot 1. After that, you'll be good to go, and it will recognize it and run in dual channel automatically.