The advent of the Beowulf cluster in 1994 provided dedicated compute cycles, i.e., supercomputing for the masses, as a cost-effective alternative to large supercomputers, i.e., supercomputing for the few. However, as the cluster movement matured, these clusters became like their large-scale supercomputing brethren — a shared (and power-hungry) datacenter resource that must reside in a actively-cooled machine room in order to operate properly. The above observation, coupled with the increasing performance gap between the PC and supercomputer, provides the motivation for a “green supercomputer” in a desktop box. Thus, this paper presents and evaluates such an architectural solution: a 12-node personal desktop supercomputer that offers an interactive environment for developing parallel codes and achieves 14 Gflops on Linpack but sips only 185 watts of power at load — all this in the approximate form factor of a Sun SPARCstation 1 pizza box.