# The Jumpers

by Kevin J. Lin

Without understanding anything about computers, it should be clear that I needed either the 1.325/1.35 volts, or the 1.275/1.30 volts. Why? Because these two have the same jumper diagram, and so therefore one must be wrong.

So which is it? The 1.35 jumper (we'll ignore the first number, it doesn't affect the solution to the problem- in the case of this motherboard, it chooses one or another depending on the CPU used). The jumper positions represent a voltage to add to the base voltage, and starting from 1.10, each jumper adds a certain value. VID1 adds .05 volts, VID2 adds 0.1 volts, VID3 adds 0.2 volts, and VID4 adds .5 volts. So to make 1.3 volts, closing VID3 adds 0.2 volts to the base of 1.1 volts. In order to make 1.35 volts, add 1.1 volts (the base), 0.2 volts (VID3) and 0.05 volts (VID1). So the 4th row and 2nd column should show VID3 and VID1 closed, instead of just VID3.

This system of using a series of on-off switches to encode many different states is known as "binary encoding" and is the foundation of virtually all computing, not just a convenient trick for hardware settings. Learn more about binary numbers at the home page for interactive binary numbers..