How Do Magnets Affect Computers?
Magnets attract certain metals like iron, nickel and cobalt. This attraction can line up the atoms in the metal so they have a north and south pole. Magnets are used in computers for various purposes, for instance in hard drives, RAM and BIOS ROM. It is important to know how magnets effect your computer so that you do not damage any of these components
Many parts of a computer can be affected by a magnet. The most commonly referred to piece of hardware affected by magnets is the hard drive. This is not exactly true. Hard drives are well protected against most magnetism, and most even use a magnet to spin, but many strong magnets and electromagnets can and will damage a hard drive. More likely to be affected is your computer's BIOS ROM, which tells your motherboard how to use basic components and boot into the operating system. Even weak magnets could damage this "permanent" memory, rendering your computer essentially nonoperational. Old 3.5-inch floppy disks can be partially erased and damaged by close contact with any magnet.
There are many different types of magnets, and their possible effects on a computer will vary by their strength. Certain alloys and the mineral magnetite can be made into permanent, but relatively weak magnets. However, there are some "rare earth" magnets that are very strong and can damage computer parts from a distance. Electromagnets are another strong type of magnet that should be kept away from computer parts.
Many people do not realize that putting refrigerator magnets on the side of the computer can damage their computer parts, but it is possible. Though it is unlikely to damage the hard drive, you may very likely damage the BIOS memory that allows your computer to boot. If you do this, you will very likely need a PC repairman to replace the CMOS chip or replace your motherboard--you will not want this to happen. Do not throw your 3.5-inch floppy disks in the same bag as your cell phone, as the phone magnet could damage the disks.
Vacuums create a magnetic field with their suction and can cause great damage to computer components, including your hard drive. Do not vacuum the insides of a computer to get the dust out; use a can of compressed air.
There is not much risk with using most magnets near computer parts except for the BIOS chip and old 3.5-inch floppy disks, but you should be careful.