The hard drive within a desktop computer runs the machine's operating system and stores all of its software programs and files. As users plan to replace or upgrade their computer's internal hard drive, they should consider the various types of hard drive interfaces on the market and the way in which those interfaces affect the functionality of a hard drive. This guide will provide a description of the features, market status, and appearance of each of the three main hard drive interfaces: IDE, SATA, and SCSI. With full knowledge of the benefits and drawbacks of each interface, users will be better prepared to select their next hard drive.
The first hard drive interface type that users need to understand is the IDE/ATA/PATA interface. All three acronyms are used to refer to the same type of technology, which can be very confusing for users who are just beginning to research hard drive interfaces. The chart below provides both the acronym and the full term for each of the three names.
Integrated Drive Electronics
Advanced Technology Attachment
Parallel Advanced Technology Attachment (used to distinguish this interface from SATA or Serial Advanced Technology Attachment)
As illustrated in the chart above, all three names for this popular hard drive interface have specific meanings that reference the technology being used. For the sake of clarity, this guide will refer to the interface by its IDE designation.
Integrated Drive Electronics (IDE) refers to the integration of the controller into the hard drive. To connect hard drives with motherboards, this interface employs a 16-bit connection in parallel orientation. Originally, this interface supported hard drives of no more than 540MB, until the Enhanced Integrated Drive Electronics (EIDE) interface came into play. EIDE interfaces are much faster and can handle hard drives that are over 50GB. EIDE versions of the IDE technology are generally more expensive than traditional IDE. The IDE interface also does not support cable lengths longer than 18 inches (or 46 centimeters).
The IDE hard drive interface has been a popular choice among manufacturers and users for well over a decade. A large percentage of hard drives currently on the market have the IDE connection, but the technology is slowly being pushed aside in favor of the new SATA interface. IDE interfaces still remain inexpensive to manufacture, resulting in lower prices on hard drives with IDE connectors.
An IDE/ATA/PATA port looks like a long, thin, rectangular box that runs horizontally along the edge of the hard drive. Within the hollow interior of the box are a number of pins that are arranged in two rows. This long port houses the cable that will connect the drive to the motherboard. Next to it is a power port containing four larger pins for a cable connection to the computer's power supply.
The Serial Advanced Technology Attachment (SATA) interface, also called Serial ATA, is more recent technology than the IDE interface is. SATA cables are slimmer and longer than IDE cables, enabling better airflow within the case of a desktop computer. It incorporates fewer pins, resulting in fewer issues with electromagnetic interference. Hard drives with this type of interface are also generally quieter than their IDE counterparts.
While IDE and EIDE interfaces have limited data transfer speeds and bandwidth, SATA can reach up to 1.5Gb per second. The brand-new SATA 2.5 interface goes even further with speeds potentially as high as 3Gb per second. SATA devices of the 2.5 standard also feature Native Command Queuing (NCQ), which lets the hard drive prioritize the read and write commands that it receives and then decide which ones will be carried out first. The SATA interface offers longer cable potential, up to one meter compared to the IDE's limit of 40 cm. SATA also provides users with "hot swapping" capability, allowing them to change out devices within the computer while the hard drive is running.
With these technological advances, SATA is quickly gaining the edge on the IDE market. However, many users with older computer systems still prefer their traditional IDE hard drives, since the acquisition of a new SATA drive would require major updates to the rest of the machine. The updates necessary to implement a SATA drive in an older computer may be extensive and costly depending on the age of the other hardware components. If users do not have a motherboard with a Serial ATA port, they may need to upgrade by purchasing a SATA card that fits in their motherboard's PCI slot. If the motherboard has no PCI slot, then users will need to buy a new motherboard that is compatible with the SATA drive that they want to install.
The SATA interface has a similar appearance to that of the IDE interface. Its cable port is box-like, sometimes with only three sides and no top side. Within the box is an arrangement of small metallic pins. However, since SATA does not require as many pins as IDE does, its port is fairly narrow and connects to the motherboard by a single slender cable. Near the SATA interface port, hard drives have a port that is connected to the computer's power supply by a cable.
SCSI stands for Small Computer System Interface. SCSI is a powerful interface type that is generally used for situations in which heavy multitasking is required, since it can sort and prioritize operations better than other types of interfaces. SCSI is vital in RAID or server environments with multiple hard drives. While there are IDE drives that can undertake these heavy tasks, SCSI drives usually accomplish them faster and more efficiently than their IDE counterparts. Older SCSI interfaces use parallel technology, while the more recent standards incorporate serial signaling for data transfer.
A typical SCSI bus can handle several unique peripheral devices at the same time, sometimes up to 15 for newer models. These peripheral devices may be internal or external, including hard drives, scanners, optical drives, and special enclosures containing several additional drives. Since several SCSI hard drives are often hooked together, they support much longer cable lengths than the IDE and SATA interfaces do. For SCSI-2, cables may reach up to six meters.
SCSI interfaces are uncommon for household computers. They are typically employed in industry and in the server rooms of large companies. Hard drives with SCSI interfaces are generally much more expensive than IDE or SATA drives. They are also louder and produce more heat, which in turn requires more extensive cooling systems.
The number of variations within the SCSI category may prove confusing and frustrating for users, since not all SCSI interfaces will work together. Some of the kinds of SCSI interfaces include SCSI-1, SCSI-2, SCSI-3, Wide SCSI, Fast SCSI, Fast Wide SCSI, Ultra SCSI, Ultra2 SCSI, and others. Users planning to purchase SCSI drives for a new server or for some other use should be sure that all of the devices are part of the same SCSI family and are fully compatible with each other. One advantage to users is that SCSI devices are often designed to work with previous generations of SCSI technology within the same line. This backwards-compatibility makes it easier to upgrade the older components of a system gradually while still enjoying some benefits of new technology.
The connectors for SCSI are similar in appearance to IDE connectors. Connectors with around 50 pins still have a box-like structure containing two parallel rows of pins. However, as the pin count increases, the connector changes its shape slightly, incorporating slanted sides rather than straight ones. Some SCSI drives have auxiliary connectors to supplement the primary connector. The SCSI cables running from the drive to the motherboard may be very wide depending on the number of pins. The power connector on the hard drive is a standard DC port with four pins, designed to link the drive to the machine's power supply.
Buying Hard Drives on eBay
New hard drives can be ordered online or purchased through a local electronics store. If you are looking for low prices on both new and pre-owned hard drives, eBay is an excellent place to begin your search.
Start on the main page and click Electronics, then Computers, Tablets, and Networking, and then Drives, Storage and Media. Next, click Hard Drives, and then choose either External Hard Disk Drives or Internal Hard Drives, depending on your needs. You will be able to narrow your search by storage capacity, by price, by brand, and by other options. You can also do a quick search for "hard drives" and save your search so that eBay can notify you anytime new listings for hard drives are posted.
You can contact eBay sellers through the Ask a Question link on the listing page or through the Contact Member link under their profile. As you approach sellers with questions about a hard drive, check for positive feedback ratings to ensure that you are comfortable purchasing from them. Some sellers also provide return policies, free shipping, or bundles that may be of interest to you.
A hard drive is a key component in any desktop computer. Since its reliability, storage capacity, and interface features directly affect the user experience, users should take care to research interface types before making a selection. With a little research and some careful consideration of the daily tasks that the computer needs to accomplish, users should be able to choose a hard drive with an interface type that will prove ideal for their needs.