IDE Cables connect from the motherboard of a computer to the hard drive, cd drive and/or floppy drive. IDE stands for Integrated Drive Electronics.
IDE is a standard interface that connects the computer motherboard to a storage device. The most common of these types of cables are the 34-pin floppy drive cable that connects from the motherboard to the floppy drive and the 40-pin ribbon cable that connects from the motherboard to the hard drive and/or the cd drive. The picture below shows both of these cables.
The IDE cable is a type of AT Attachment which has had speeds from 33, 66, 100 and 133 MB/s. A faster cable can go in a slower hard drive but a slower cable will decrease the speed of a fast hard drive.