Hard drives are mechanical devices and they are much slower than computer processors or memory. To get the most out of your hard drive, manufacturers use just a small amount of computer memory built into the hard disc drive to buffer information being written to, or read from the hard drive. This small chunk of memory is called ‘cache’. Information that is accessed frequently is kept the cache memory. The cache memory allows the computer to maximize throughput across the connector bus interface (USB, Firewire or eSATA), increasing the total throughput between the drive and the computer. While there’s a limit to the benefits as provided by cache memory, in general more cache memory is better.