Is it a card for the secondary CPU Slot (IE dual P2 design)? I think they had to have 2 cards or CPU's inserted in order to work properly, so that is proabaly it.
Way to go Homestar! It's a CPU terminator card for dual-cpu systems that only have 1 CPU. The system it was taken from was a Xeon (P3 version) with a single 1 GHz processor.