are you trying to use 3GB of RAM or are you trying to hit 3Ghz? you can't really hit 3GB of ram on a P4 DDR board very easily sure as hell not with Corsair XMS..I don't think they even make a 1GB stick, let alone a 2GB stick of XMS....I can't find it on their site. The only way you can use 3GB of DDR anyway, and that's IF you pick up a board that supports that (which the P4B533 does NOT), is to do it in 4 banks or less, which means 1, 1GB stick and 1, 2GB stick....good luck finding anything above about 512MB in DDR, and even the DDR you CAN find is only PC2100...it ain't happenin' dude.