Hard Drive Overclocking: Is It Possible?
Now, if you know anything about hard drives, you'll see what a delicate operation this is. The rotation speed of a hard drive is kept fixed for a reason: hard drives, especially the extraordinarily dense hard drives we see today, require absolute precision, and overclocking threatens to break that precision.
Unlike typical methods of overclocking other computer components, you usually cannot simply increase the voltage, as the voltage is not directly related to the rate at which the spindle motor works, as the hard drive is mechanically constructed to spin at a consistent rate. However, this is not necessarily true of all hard drives—it's hard to know without their proper specifications—and it may be possible that by increasing the voltage you may also increase the rotation. Even so, you may also need to hack the read/write heads that contact the spinning drive so that they are properly synchronized, and at least this here hobbyist isn't too sure on how to manage this. If this is to be attempted, be sure to increase the voltage only be small increments in order that you don't fry the whole shebang. It is also absolutely paramount that you provide adequate heat venting as well.
Accounts from those who have successfully overclocked their hard drives are generally don't sound successful, resulting in everything from shattering hard drives to bad burns. Even if you do manage it, overclocking is a surefire way to shorten the lifespan of your drive. So, generally, this is not something you want to try unless you really know what you're doing.