In a computer, the Hard Drive (HDD) is used for storing and retrieving data such as the Operating System, programs, and user files. This data is retained even when the computer is powered off.
In a desktop computer the Hard Drive comes in a standard size of 3.5 inches while a laptop computer contains a smaller 2.5 inch Hard Drive. There is more information about the 2.5 inch Hard Drive on the Laptop page.
The Hard Drive is connected to the motherboard via an interface cable. There are three main types of Hard Drive interface including the older IDE (Integrated Drive Electronics) also called PATA (Parallel ATA), the new SATA (Serial ATA), and SCSI (Small Computer System Interface) which is mainly used on servers and in industry.
Hard Drives - SATA & IDE
The two main types of Hard Drive on a Home Computer include the older IDE Hard Drive, and the new SATA Hard Drive which are pictured above. They are both the same size and look identical except for the power and data connectors.
Why should i buy a Hard Drive for my desktop computer?
Hard Drives are mechanical devices with moving parts which can fail resulting in the loss of all your data although they are relatively cheap and easy to replace. You may also want to add more Hard Drives to your computer for additional storage space.
Which type of Hard Drive should i buy?
First you need to look at your computer's motherboard or look in your motherboard manual and determine if it contains the older IDE connectors or the newer SATA connectors. The motherboard may even contain both types of connector.
If the motherboard has IDE connectors then you will need an IDE (PATA) Hard Drive. There are usually two IDE connectors on the motherboard and each connector can control up to two drives allowing a total of four drives to be connected in total. A newer computer will most likely have SATA connectors which allow one drive per SATA connector. If you intend to add more internal Hard Drives to your computer then you will not only need a spare data connector but will also need room to install the Drive into the case.
Once you have determined the type of Hard Drive to buy then you will want to buy one which has the largest capacity you can afford as well as being fast. The capacity of the disk determines how much data can be stored and is measured in GB (Gigabytes) or TB (Terrabytes). The speed of the Hard Drive depends on how fast it spins and common speeds include 5,400rpm (revolutions per minute) or 7,200rpm. It is recommended to get the faster drive.
Looking at the photo of the SATA connectors above you will see that four connectors are blue and two are white. The blue connectors on this motherboard are SATA2 (SATA II) and the white connectors are SATA3 (SATA III). SATA2 is a second generation interface which runs at 3 Gbits/s (300 Megabytes per second) and SATA3 is a third generation interface running much faster at 6 Gbits/s (600 Megabytes per second). First generation SATA1 used to run at 1.5 Gbits/s (150 Megabytes per second). If your motherboard supports SATA3 then it makes sense to buy a SATA3 Hard Drive that takes advantage of this speed. If you only have SATA2 connectors on the motherboard then it will still work okay with a SATA3 Hard Drive as it is backwards compatible but it will work at a slower speed.
You may notice when looking at the specifications of Hard Drives that they have different size caches. This is embedded memory inside the Drive which is used as a buffer to speed up data transfer. Generally a larger cache (measured in Megabytes) is preferred.
The following Hard Drive brands are popular:- Western Digital, Seagate, Maxtor, Hitachi, and Samsung.
Today you can purchase Green Hard Drives which are available from Western Digital and Seagate. They are marketed to be enviromentally friendly by using less power and will run cooler and quieter than a normal Hard Drive.
You can also add an external Hard Drive to your computer which is usually connected by a USB (Universal Serial Bus) connector. This is a good idea if you do not want to fit an internal Hard Drive or there are not enough Connectors or space to fit the drive inside the case. You also have the option to disconnect the external Hard Drive and use it on another computer. It will however be slower than an internal Hard Drive.