Is a hard disk internal or external memory?

A hard disk can be either internal or external memory. The key difference lies in where the hard disk is located and how it connects to the computer.

What is a Hard Disk?

A hard disk is a data storage device used in computers. It contains one or more platters coated with magnetic material, which store data as magnetic polarities. Hard disks come in two main types – internal hard disks and external hard disks.

Internal Hard Disk

An internal hard disk is located inside the computer case and directly connected to the motherboard or a controller card. It draws power from the computer’s power supply unit. Internal hard disks come in standard sizes like 3.5 inches and 2.5 inches and are usually installed in drive bays in the computer case.

Examples of internal hard drives include HDDs (hard disk drives) and SSDs (solid-state drives) that are connected via SATA, SAS or IDE interfaces on the motherboard. Internal hard drives offer faster read/write speeds as they directly interface with other internal components.

External Hard Disk

An external hard disk is located outside the computer case in its own enclosure. It connects to the computer via an external interface like USB or Firewire. Most external hard drives today use a USB interface to connect to computers and draw power over that same USB cable.

External hard drives come in a range of sizes from portable smaller drives to larger desktop models. Portable drives use 2.5-inch hard disks, while desktop models typically use 3.5-inch drives. Notable examples include portable HDDs and SSDs from brands like Seagate, WD, Toshiba, etc.

Differences Between Internal and External Hard Disks

There are some key differences when it comes to internal vs external hard drives:


The most obvious difference is that internal hard drives are installed inside the computer case while external hard drives are located outside the case in a separate enclosure.


Internal hard drives connect directly to internal ports like SATA on the motherboard. External drives usually connect over USB, Firewire, eSATA or Thunderbolt interfaces.


Internal hard drives are faster as they directly interface with the system bus via SATA or IDE connections. The maximum interface speeds are higher than USB or other external interfaces.


Internal drives draw power directly from the computer’s PSU. External hard drives are powered over their interface cable, usually USB, or sometimes by a separate power adapter.


External hard drives are highly portable and can be carried around or used with different computers easily. Internal drives are not meant to be portable and are designed to stay within the computer case.

Uses of Internal Hard Drives

Internal hard disk drives are commonly used as the primary drive in computers and servers to store the operating system and applications. Some common uses include:

  • Boot drive to store OS like Windows, Linux distributions, etc.
  • Drive to store software, games, programs on a computer
  • Primary storage drive for data in servers and data centers
  • Media storage for movies, photos, music on home PCs
  • Drive for backups using software like Apple Time Machine

Internal hard drives are also often used in RAID configurations to provide increased redundancy, performance or large volumes of storage in servers.

Uses of External Hard Drives

External hard disks serve as expanded storage space that can be accessed easily. Common uses include:

  • Backing up computers by storing files externally as a safeguard against system failure
  • Expanding storage capacity of a system easily without opening up the computer
  • Portable file storage that can be carried around anywhere
  • Sharing and transferring large amounts of data between computers with ease
  • Expanding storage of games consoles like Xbox, PlayStation, etc.

Most external hard drives today use USB interfaces. eSATA and Thunderbolt interfaces allow even higher speeds but are less common.

Internal vs External for Gaming

For gaming PCs, internal hard drives are preferred as the boot drive as they provide faster speeds and response times while loading games and levels. An SSD is ideal for quick loading performance. However, external drives can be used to expand storage for large game libraries.

Advantages of Internal Drives for Gaming

  • Faster interface like SATA allowing quick loading
  • Lower latency and quicker response times
  • Ability to directly connect multiple fast internal drives in RAID

Advantages of External Drives for Gaming

  • Easy plug and play storage expansion
  • Ability to share games between different systems
  • Portable to carry game libraries anywhere

Reliability Differences

Historically, external hard drives used to be less reliable than internal drives as the external enclosure was a point of failure. However, reliability has improved significantly today for external hard drives.

Enterprise-grade internal hard drives designed for 24/7 operation still offer the highest reliability and workload ratings. But many portable external HDDs and SSDs today also provide excellent reliability while offering the convenience of plug-and-play storage.

Factors Affecting Reliability

  • Quality of hard disk components – platter, heads, etc.
  • Interface connectivity with the computer
  • Shock resistance capabilities in case of drops
  • MTBF (Mean Time Between Failures) ratings
  • Warranty period offered

Internal vs External Hard Drives for Backup

Both internal and external drives can be used for backup purposes, with some key differences:

Internal Hard Drive for Backup

  • Convenient to backup system drive to secondary internal drive
  • Faster transfer speeds with SATA interface
  • Can use RAID 1 mirroring between two internal drives
  • Backups are not protected if computer is lost, stolen or damaged

External Hard Drive for Backup

  • More convenient for offsite backups that can be stored externally
  • Backups protected even if original computer fails
  • Slower transfer speeds in most cases
  • Portable to be carried and used with multiple devices

For robust backup, using both internal and external drives is recommended. Critical backups should be stored offsite on external drives in case of theft or disaster.

Cost Perspective

Internal hard drives generally cost less compared to portable external hard drives of the same capacity. This is because external drives come with additional components like the enclosure, USB interface circuitry, power adapter etc.

However, external HDDs and SSDs are falling in price and routinely see discounts and deals. So the pricing gap has reduced between internal and external drives in the case of portable models. For desktop drives, internal HDDs tend to be more affordable per TB of storage.

Key Factors Affecting Cost

  • Capacity – Larger drives cost more
  • Interface – USB drives cheapest, then Thunderbolt/eSATA
  • Hard disk components – SSD most expensive, then enterprise HDDs
  • Brand name and features
  • Regional taxes, duties and supply-demand

Choosing Between Internal and External Drives

So which type of hard drive should you choose for your needs? Here are some general guidelines:

When to Pick Internal Storage

  • For primary boot drive to store OS and programs
  • For gaming systems requiring fast loading and performance
  • For frequently accessed applications and files
  • For RAID drive arrays in servers and workstations
  • For video editing rigs needing max throughput

When to Choose External Storage

  • For backups and archives that can be stored offsite
  • To easily share and transport large amounts of data
  • For secondary media libraries and drives
  • To expand storage capacity easily without opening the computer
  • For use with multiple devices like PC, console, laptop, etc.

For most home users, having the OS and apps on an internal drive and using external drives for data archives, backups and transfers makes optimal sense.


Internal hard drives are installed inside the computer case while external hard drives are located outside in a separate enclosure. Though internal drives are faster, external HDDs and SSDs are highly portable and can be used across devices. For most users, having both internal drives for everyday performance and apps, along with external drives for expanded capacity is the recommended solution.

This covers the key differences between internal vs external storage and their respective uses. Both types of drives continue to become faster, higher capacity and more reliable as technology improves. But each still has merits in specific use cases. Determining your exact needs and workload patterns makes choosing the right drive easy.

In summary:

  • Internal drives are faster, while external storage provides easy portability and sharing.
  • For gaming PCs, internal hard drives provide better performance as the boot drive.
  • External drives are more suitable for backups to be stored offsite and large media libraries.
  • Internal drives generally cost less per TB, but external drive prices are competitive for portable models.
  • Consider both for primary fast storage and expanded capacity respectively.