Not sure if it's been posted, but don't expect the tracer to light up on x79. They don't work - get the ones with the tall heatsink. I bought the 4xddr3-1866 4gb tactical tracers and am happy with them. I popped them in and keyed in 2133 9-9-9-27-1T-1.69V. One day I'll see what else I can do with them. It kills me that the lights and probe doesn't work though.