i may have a theory about this. the mobo in the xps 630i is a dell/nvidia 650i sli mobo with the highest supported cpu fsb of 1333mhz. now this is where it gets confusing. i cant change the fsb(QDR) in the bios at all. its at 1333 and if i change it to 1334 the pc doesnt post. but if i load vista and go into the nvidia control panel i can overclock the cpu to 2.7GHz from 2.5GHz(stock) without changing any voltages. so with the cpu fsb at 360mhz that means the QDR is 1440mhz. and i make this oc profile and save and create a auto load rule so after i login to windows after 3 sec it will load the oc settings. now why can i oc with the software but not in the bios? its very frustrating and i would like to be able to oc in the bios instead of software. but since the mobo has max fsb of 1333mhz for cpu, is that why i cant raise it because its maxed already? but why does it work with the software. and the oc is true after software oc it shows in cpu-z and 3dmark vantage. so if any one can explain why i can software oc but not bios oc its greatly appreciated.