High-performance computing (HPC) clusters can be composed of large numbers of servers, where the total physical size, energy use or heat output of the computing cluster might become a serious issue. Furthermore, there are requirements for dedicated communications among the servers that are somewhat unique to clusters. Because small design differences amount to large benefits when multiplied by the number of servers in the clusters, we are seeing the emergence of server designs that are optimized for HPC. Sometimes these are designs targeted at large, public Web operators, such as search engine firms, that deliver similar benefits in HPC clusters, but they can also offer features only appropriate for HPC users. For example, if the system were designed to provide the cluster interconnect differently, there might be a significant cabling reductions possible.