check your jumpers on your MB. Should say in you MB manuel how to set them up for 133 FSB. Also when you boot up the pc, get into the bios (usually holding down the "delete" key will get you in there. Make sure your FSB is set at 133 and not lwr, usually they come stock from factory at 133. What kind of MB are you running and does it support the 2400 2.0Ghz cpu?