Need more processors? No problem, just add another board onto the HTX-Pro bridge, which is a Hypertransport expansion chip.

"The boards are the QK8S and the QK8S-8P. The first of these uses the AMD 8000 series chipset to supprt four Opteron 800s and 128GB of registered DDR 266 SDRAM, or alternative 64GB of DDR333/400 memory. The 8P can support 256GB of DDR266 or 128GB of DDR333/400."