Alien Babel Tech dug up a video from Cooler Master showing off "53Ghz in one case."
The title of the video is a bit misleading as Cooler Master has crammed five full systems into a single Cooler Master ATCS 840-Tower, not overclocked to the extreme like we had hoped.
Each system is powered by a 2.66GHz Intel quad core chip. To reduce power consumption and noise, 2.5" drives were used, although they aren't using SSD's for some reason.
Tieing everything together is a single Cooler Master Real Power M 1000W power supply. The PSU is powered on before each of the five independent systems, then then each can be started up one at a time.
Cooler Master will have the system on display at CeBit 2009 if you wish to see it in person.