The Complete Guide to Buying Internal Hard Disk Drives

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The Complete Guide to Buying Internal Hard Disk Drives

A computer's hard drive performs the vital roles of information storage and retrieval. Hard disk drives (HDDs), the most common type of hard drive for personal computers, are comprised of one or more disks or platters and an actuator arm with magnetic heads that read and write information on the disk. Hard disk drives employ random-access data retrieval, so that data can be stored and read in any order, not only sequentially. While solid-state hard drives with flash memory offer improved durability and superior speed, hard disk drives remain a dominant method of storage, offering significantly higher storage capacity, with much lower cost per unit of storage.

When selecting an internal hard disk drive for a computer, there are several factors to consider. Buyers can compare models within their price range by looking at specifications connected with storage capacity, performance, and data safety. Compatibility with the computer itself is also essential. As computer technology constantly develops, consumers should research the latest offerings and assess which internal hard disk drive is right for their needs.

Hard Disk Drive Performance

When manufacturers and technology experts speak about a hard disk drive's performance, they are referring to how quickly data is transferred within the device itself, or between devices. There are several specifications connected to drive performance, including interface, data transfer rate, spindle speed, and cache or buffer size. Experts recommend prioritising performance over capacity when shopping for an internal hard disk drive to run programs.

Interface and Data Transfer Rate

The Serial ATA (SATA) interface standard dictates how quickly a drive connects to a host, such as a computer or server. Therefore, the SATA interface standard is indicative of how fast a given consumer-grade internal hard disk drive performs. There are multiple generations of SATA, and each successive one is better-performing.

The data transfer rate for a device is expressed in megabytes per -second (MBps) or gigabytes per second (Gbps). SATA III has a data transfer rate of 6Gbps, SATA II a rate of 3Gbps, and SATA I a rate of 1.5Gbps. To give buyers an idea of what these figures mean in actual practice, a SATA III drive could transfer a compact-disc's worth of information, about 700MB, in one second. That said, data transfer rates quoted by manufacturers are based on best-case scenarios, so consumers can expect the actual rate to be somewhat slower.

The interface must be supported both by the internal hard drive and the computer or other host. Most computers are backward-compatible with earlier interface generations, but not all are compatible with the latest ones. Older computers may have a Parallel ATA (PATA or IDE)) interface, which is wider and slower than SATA.

Spindle Speed

Spindle speed, also called rotational speed, indicates how many rotations-per-minute (RPM) the hard drive disk makes. The faster the speed, the more quickly information can be written on and retrieved from the disk. The average spindle speed is 7200 RPM, but faster and slower models are also available, with spindle speed usually reflected in the price. Hard disk drives marketed as energy-efficient spin at slower speeds like 5400 RPM, consume less power, and cost less. These may be an excellent choice when choosing an internal hard drive whose primary function is storage.

Cache or Buffer Size

Every internal hard disk drive has a cache, which acts a buffer memory for frequently-used information. Retrieval speeds from the cache are much faster, and the larger the cache or buffer capacity, the faster the overall performance.


Capacity expresses the amount of data an internal hard disk drive can store. It is expressed in gigabytes (GB) or terabytes (TB), where one terabyte roughly equals 1,000 gigabytes. Storage capacities can range anywhere from less than 100GB to upwards of 1TB.

How Much Storage is Enough?

With such a range of choices, and the maximum amount ever-increasing, consumers are left wondering how much storage they may actually need. Because higher storage capacities can drive up prices, this question is worth some thought. Much depends on what kinds of files the user generally stores on their computer. Users who store videos and record television on their computer would do well to choose the highest capacity available. Professional photographers who store their work in RAW format, those who work with computer-aided design, serious gamers, and music lovers with extensive digital libraries should also opt for a large storage capacity.

On the other hand, consumers who use their computer mainly for word processing documents, spreadsheets, and a modest collection of photos and music, may find that smaller storage capacities are perfectly sufficient.

When estimating how much storage they need, it helps buyers to keep in mind the average size of some common file types, as outlined in the following table.

File Type

Typical Size

Word-Processing Documents

A few hundred KB, possibly a few MB for larger files


A few hundred KB, possibly a few MB for larger files

Music Files

Average song in MP3 format is several MB

Digital Photos

Several MB or tens of MB for professional-grade formats

Digital Videos

May be hundreds of MB or even a few GB; for example, one hour of DV-format video requires about 12GB of storage

Non-Compressed Digital Video

Standard-definition video may take up to 2GB of storage for one minute of footage; high-definition with resolution of 1920 by 1080 requires 9.38GB for one minute of footage

Shoppers should carefully consider the type and quantity of files they expect to store on their internal hard drive. For reference, one kilobyte is 1024 bytes, one megabyte 1024 kilobytes, one gigabyte 1024 megabytes, and one terabyte 1024 gigabytes. A byte is a unit of information, comprised of eight bits, that is, eight 1's or 0's.

Potential Space-Recognition Issues

Some computers, particularly ones running on older operating systems, may have trouble recognising space on drives larger than 2.19TB. There are solutions for this issue, including hardware-based host bus adapters (HBAs), and software applications that facilitate access to that space.

Data Safety

Hard drives are prone to damage as a result of physical impact, moisture, heat, and vibration. While this issue is of less concern for desktop computers, it should be kept in mind when shopping for an internal hard disk drive for a laptop computer, which is much more likely to be bumped, dropped, or jostled. Consumers who plan to travel extensively with their laptops may want to look for an internal hard drive that has extra layers of protection to help it withstand physical shocks.

Backing Up Information

No matter how reliable and sturdy a hard drive, there is always the possibility that, due to drive failure, a virus, or physical damage, data may be partially or completely lost. For that reason, it is very important that computer users back up their data using one of a number of ways, including an external hard drive or online cloud storage.

Form Factor and Compatibility

Most internal hard drives have a form factor of 3.5 inches; however, more and more models feature a 2.5-inch form factor. The form factor is an important consideration insofar as it needs to be compatible with the bays and caddies in the computer case. If a computer case is not designed to accommodate a 2.5-inch form factor, installation can be problematic. Even if it is possible, it may require special trays and brackets to mount. Therefore, buyers should check what form factor their computer case is capable of mounting before purchasing a hard drive.


If a computer has multiple internal hard drives, users can choose to use the hard drives separately, or link them together via a system called RAID (redundant array of independent disks). RAID can increase drive efficiency and performance, making it particularly useful for workstation applications and other data-intensive programs. RAID uses two techniques: striping, which distributes a single data stream to two or more drives for faster writing and reading; and mirroring, in which identical copies of the same data are sent to multiple drives. There are a few different versions of RAID; RAID 0, RAID 1, and RAID 10 are the most common for consumer use.

How to Buy an Internal Hard Disk Drive on eBay

eBay has a vast selection of internal hard disk drives, in a range of capacities and speeds. To start your search, simply go to eBay's home page,, locate the search bar, and enter keywords like "500GB internal hard disk drive&". When you have your initial search results, you can refine them by choosing your price range, preferred manufacturer, and certain specifications.

Reading Item and Seller Information

Always read the full listing for any item that interests you. The item description contains important information, including product specifications and item condition; note whether there are additional postage fees, and what the payment requirements are. If you need clarification about anything, eBay makes it easy to ask the seller a question..

Getting to know a bit more about the seller is also advisable; have a look at their feedback score and what past customers have said about them, preferably those who bought an item similar to yours. This helps you assess how reliable they are, so you can buy with confidence.


An internal hard disk drives is a computer's storage centre, holding vast amounts of information connected to everything from software to spreadsheets. Performance, capacity, and data safety are three major areas of focus when shopping for an internal hard disk drive.

Performance depends largely on speed, which is affected by several factors, including interface, data transfer rate, spinning speed, and buffer size. Capacity refers to how much information a drive can store, and the range in consumer models stretches from a few hundred gigabytes to several terabytes. Because higher capacities usually mean higher prices, buyers should try to realistically assess how much data storage space they need based on their computing lifestyle. To protect the drive and data from physical damage, laptop owners can look for models featuring protective layers. Additional considerations include backing up data, form factor, and RAID.

Whether upgrading to a faster, larger-capacity drive, or building a computer from scratch, informed consumers can find the right internal hard disk drive for their needs.

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