Computer Parts

Why do hard drives make noise when they're retrieving data?
Answered by HowStuffWorks
  • HowStuffWorks


  1. It's a noisy world that surrounds us, and computers do their part to contribute to the din. Inside the casing of a hard drive, an arm holds read-write heads that can move hundreds of times a second as they slide around over the 5-inch (12.5 centimeter) diameter of the disk. These drives aren't solid state, so it's a feast of movable parts. The movements of these drive heads cause the whirring sound you hear whenever you've caused your computer to have to do anything that taxes its brain, like opening a program, finding a file or saving a file. For example, here's what happens when you open a typical Excel file:

    • The Excel application needs to load, along with dynamic link libraries that support it. The files might be 10 to 20 MB and are scattered throughout the disk.
    • The data file has to load. For this to happen, the operating system has to locate the folder and file and present it for work.
    • If physical RAM is full, meanwhile, the operating system has to unload parts of physical RAM and save them to the paging file.

    With the drive heads doing all of that moving, it's no wonder your computer churns.
    Not all drives are so loud. Possibly a bit quieter than their larger internal cousins, portable external hard drives are available for on-the-go users who like to bring their large blocks of data with them or for those who enjoy a portable backup disk. A portable hard drive is a form of magnetic removable storage, its popularity arising from its being totally external, hand-held and USB-enabled. Like the hard drive that is part of a personal computer, portable hard drives contain both the drive mechanism and the recording media in a sealed case. They almost always connect to your computer via a USB cable, which means it is extremely easy to connect and disconnect them. Following installation, the portable hard drive becomes an automatically available storage drive -- another drive letter your computer can use, just as if you had another hard drive inside.


    And for those bothered by internal drives that make lots of noise when they have to do any work, help may be on the way. They're not in widespread use in traditional consumer computing yet, but solid state drives may one day be as common as their older hard drive cousins -- no moving parts to add to the noise.

    More answers from HowStuffWorks »

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