NAMD Wiki: NamdOnInfiniPath
The InfiniPath HTX adapter utilizes the new standard HTX slot on the motherboard to connect directly to the AMD Opteron CPU via HyperTransport. Externally, it utilizes standard InfiniBand switching fabrics. More information can be found at http://www.pathscale.com/infinipath.php
See also NamdOnInfiniBand.
The folks at PathScale have ported and benchmarked NAMD on their compiler and interconnect, with complete directions at http://www.pathscale.com/building_code/namd.html