Jumper

Updated: 06/19/2020 by Computer Hope
Computer jumper

Jumpers allow the computer to close an electrical circuit, allowing the electricity to flow on a circuit board and perform a function. Jumpers consist of small pins that can be covered with a small plastic box (jumper block), as shown in the illustration. Below the illustration is a picture of what jumpers may look like on your motherboard. In this example, the jumper is the white block covering two of the three gold pins. Next to the pins is a silkscreen description of each of the pin settings. The picture shows pins 1-2 jumped for Normal mode, 2-3 for config mode, and when open, the computer is in recovery mode.

Tip

A jumper may also be referred to as a jumper shunt or shunt.

Jumpers manually configure computer peripherals, such as the motherboard, hard drives, modems, sound cards, and other components. For example, if your motherboard supported intrusion detection, a jumper can be set to enable or disable this feature.

In the past, before plug and play, jumpers were used to adjust device resources, such as changing what IRQ the device uses. Today, most users don't need to adjust any jumpers on their motherboard or expansion cards. Usually, you are most likely to encounter jumpers when installing a new drive, such as a hard drive. As shown in the picture, ATA hard drives have jumpers with three sets of two pins. Moving a jumper between two pins changes the drive from primary drive, secondary drive, or cable select.

Jumpers on back of IDE hard disk drive

Tip

Some documentation may refer to setting the jumpers to on, off, closed, or open. When a jumper is on, or covering at least two pins, it is a closed jumper. When a jumper is off, covering only one pin or the pins have no jumper, it's an open jumper.

Caution

When changing the jumpers on any device, the device and your computer needs to be turned off. Also, whenever working in a computer or with any electronic device, be aware of ESD.

How many jumpers are on a motherboard?

Every computer motherboard is different, which means there is no way to know how many jumpers are on a motherboard, unless you know the motherboard's manufacturer and model number. Once this information is known, this question can be answered by consulting the motherboard's documentation.

Dip switch, Electronics terms, Hardware terms, Jump, Master, Slave