The Mushkin XP2-6400 CL4 4GB Kit looks very nice and comes in a unique package. The memory performs as it should, right out of the box and has a bit of headroom at the CL4 rating. The big downside is the fact, that the memory does not scale well with additional voltage. No matter how much is applied, the maximum possible is not raised, but even drops at CL5. The great upside of the kit is, that it manages to break the 1000 MHz barrier easily at default voltage. This is really what saves the kit and does make it interesting for people who do not have the possibilty of raising the default JEDEC voltage. Another nice addition is the possibilty to run the memory at CL3, even with default voltage, but it does not manage 800 MHz, no matter with what voltage.