Intel produced DX4s with two clock speed steppings: A 75 MHz version (3x 25 MHz multiplier) and a 100 MHz version (usually 3x 33.3 MHz, but sometimes 2.5x 40 MHz or 2x 50 MHz). OverDrive editions of the DX4 had locked multipliers, and therefore can run only at 3x the external clock-speed.