Mubbers must have the P4S800, which is based on the SiS 648FX chipset. It's the only p4 board that I could find that supported 800FSB processors and only had 3 DIMM slots. As such, it IS NOT a dual channel board. Also... read the website, it only supports 1 DIMM when using PC3200. I say return the mobo and get something based on the 865 chipset. If you had gotten the P4S800D, it would have been based on the 655TX chipset, which is dual channel and has 4 DIMMs... also as far as the PSU goes, try to pick up either an Enermax or an Antec. The PSU is NOT the place to start skimping and going "budget".