The highest clocked 386 CPU, and one of the most popular ones, was the Am386DX40, so your computer would likely have had a 40 MHz part. It is a common misconce

The highest clocked 386 CPU, and one of the most popular ones, was the Am386DX40, so your computer would likely have had a 40 MHz part. It is a common misconception is that the MHz displays from this era had any kind of communication with the CPU or motherboard. They don't -- they are dumb devices that can switch between showing two arbitrary patterns on the LED display and are "programmed" by painstakingly setting jumpers on the back. Often when using 2-digit displays for computers with 3-digit clock speeds they would be programmed to display "HI" and "LO" instead of a number. So when your display showed "20" that doesn't mean the CPU was running at 20 MHz. It might have been, because 386 CPUs always ran at the bus speed and 20 was a common 386 speed, but things get a lot more complicated when you move to the 486 platform with internal clock multipliers. My 486 DX4/100 (33 MHz bus speed, 3x multiplier) has a turbo button that when disengaged lowers the effective speed of the system to something roughly like a 486 DX50. But this is not an exact science and does not in fact mean that the CPU is running at 50 MHz.