Actually, the ECS RS400-A motherboard supports LGA775 Pentium 4 and Celeron processors running on either the 800MHz or 533MHz FSB, but what really makes this motherboard unique is that it has both a PCI Express x16 and physical 8xAGP slot. Other onboard goodies consist of a 10/100 network card, onboard graphics care of the Radeon Xpress 200 chipset, support for either DDR or DDR-2 memory, and 7.1 channel audio through the 'SB400' IXP400 southbridge.