Problems in the mailbox Yes, the magnet can destroy the hard drive, but you need a stronger magnet than the one attached to the refrigerator magnet. This is a video of the aToshibanotebook destroyed by amagnet. The magnet that causes damage is the fish tank cleaner. Want a magnet that\'s guaranteed to destroy the hard drive. - Or a CD/DVD drive? You need something like this. Inch n52 nd disc magnet with a pulling force of about 450. Clip your hand between this and a piece of magnetic metal and you may lose your hand. Not only will this erase the hard drive, it will also release the hard drive with the CD/DVD drive and any fan. I know. I used one!