SGI Altix XE340
The Altix XE340 contains two SuperMicro X8DTT motherboards with InfiniBand. Each has two Xeon X5570 quad-core 2.93GHz processors and 48GB of ECC DDR3 RAM, for a total of 16 cores (32 threads) and 96GB of RAM.
Unlike SGI's previous MIPS-based servers, this is not a single-system-image configuration and it's basically just two off-the-shelf PC servers in a single 1U rackmount enclosure.
I've later added an ATI FirePro V3900 graphics card.