Likely, you're bios has an incorrect cpu fsb setting. I'd guess you have a 2.4ghz cpu with a 18x multiplier and a 533fsb(133x4). So in the bios it'd be 133x18=2400mhz, but if it got set to 100mhz(400fsb), it'd be 18x100, which'd be 1800mhz. If your bios has an adjustable fsb, adjust it from 100mhz(400fsb) to 133mhz(533fsb). If most of that just blew over your head, just read the above sentence, go to you bios(press f1, f2, del, or whatever your bios's key is), and look for a fsb setting(you may have to enable fsb adjustment in an option box to be allowed to change the fsb if it's grayed out). It should be set to 133mhz, but it likely is set to 100mhz if it's reporting 1.8ghz.