the motherboard " Gigabyte RXZ Series 7VT6000-RZ " has a cpu jumper. If the jumper is on the motherboard it sets the motherboard fsb at 100Mhz. If the 2 pin jumper is removed from the motherboard it sets the fsb to 133/166Mhz and auto detects to either of those two settings. sydhall had a problem a few weeks ago in trying to get a sempron working at the correct speed. It was just running at 100Mhz. Removing the jumper brought the sempron running at the correct speed.