OCC has published a review on the Geil Black Dragon PC3 12800 CAS 9 6GB

I was able to raise the base clock of the processor all the way up to 167MHz, which allowed the memory to achieve 2000MHz, which is a 400MHz overclock. Now to achieve this, I did need to raise a few of the voltages. The memory voltages needed to be raised to 1.72v to keep them operating stable, QPI volts up to 1.44v and the IOH up to 1.22v.

Geil Black Dragon PC3 12800 CAS 9 6GB Review