The real problem with a QS CPU in a cube isn't the buss speed, it's making it fit physically. If you figure that out, post pictures. I have a QS dual 867 CPU that I'd like to use in a cube. Buss speed is easy, since the multiplier resistor locations are posted on xlr8yourmac.com. The dual 500 is an easy CPU upgrade. Lay the coil on its side and drill holes in the heat spreader plate so it can rotate 90° to hit both chips.