Solid State Drives Explained

Faster, quieter and more secure.

Solid State Drives Explained | Internal and External SSDs

Solid State Drives Explained | Internal and External SSDs

Hard drives have always been a vital part of a computer – it’s where information is stored, so that when you save your documents or images, they have somewhere to actually go. The technology behind them has changed a fair amount over the years but one of the most significant changes is the arrival of SSD, or Solid State Drives.

SSDs store information on flash memory chips, similar to the memory on a USB stick, as opposed to using physical disks like a traditional drive. This does away with the need for moving parts, which makes the entire operation faster and quieter.

SSD drives are speedy, efficient and can come in both internal and external types, depending on your needs.

Let’s take a look at solid state drives more in-depth.


PC owners have a choice to make for storage space – the traditional HDD or the new SSD standard. There are many advantages of solid state drives over hard disk drives, including:

  • SSDs are smaller and lighter, making them easier to fit into low-profile PCS
  • SSDs consume less power, so they are easier on PSUs and the environment
  • SSDs are much faster than HDDs, having no mechanical parts to move
  • SSDs are also silent for the same reason
  • HDDs have the advantage in terms of size for money, but SSDs are getting cheaper

Differences Between Internal and External SSDs

SSDs, like HDDs before them, come in two distinct types – internal and external. Internal SSDs are fitted inside a PC or laptop, while external SSDs sit outside the machine. The difference is very important and gives consumers a vital flexibility in how they solve their storage issues.

Differences Between Internal and External SSDs

Internal drives are best suited to people who know about building computers. Installing them requires opening the machine and connecting the appropriate cables. For those who know all about this, an internal drive is great because it takes up no additional space.

External drives are best suited to those who don’t know about PC building, or who simply want mobile storage. These drives plug in via the mains and a USB cable, so they can just sit on a desk. They take up space, but are very easy to transport and use.

Solid State Drive Features

OS Compatibility

All SSD drives are, broadly speaking, compatible with all OS systems. The key difference is in how you format the drive for use. However, it’s worth checking before buying with a quick google search, to ensure the drive works with the PC or Mac setup you have.


The storage capacity of an SSD is measured in GB or gigabytes. While HDDs are known for bigger storage capacity, a reasonably priced SSD with 250GB or more space can now be purchased. You need to judge how much you require, bearing in mind that it’s wise to go larger to anticipate future needs.


Most internal SSDs use the SATA, Serial ATA interface. This is a largely universal system for connecting drives using a simple plastic cable to the motherboard. This gives speeds up to 600 MB/s.

You can also find SAS and FC interfaces, but these are more specialist. PCIe drives connect directly to the motherboard and while efficient, tend to require a specific setup, so always check compatibility. External models are typically connected via a USB cable.

Sequential Read/Write Speed

A huge factor in choosing an SSD is speed. Though the difference is negligible for day-to-day use, gamers and power users inevitably want faster speeds. Read speeds of (potentially) 500 MB/s are ideal, but this does come down in practice. Sequential Read/Write refers to the speed of reading or writing (opening or saving) large files, such as videos.

Random Read/Write Speed

The random speed of a drive refers to the speed of creating or opening small files, so this tells you how good the drive is for quickly opening documents or performing simple tasks, a measure of the speed of using general Windows programs, for example.

NAND Technology

NAND refers to the flash storage that makes SSDs possible. There are two types of NAND, Single-Level Cell and Multi-Level Cell, with SLC being the more expensive and better performing. However, this distinction will rarely make a large difference to the average consumer.

Security Encryption

Some SSD drives come with built-in hardware encryption. This means that information is encrypted as it’s stored to the drive, automatically, without you having to do anything. The information is decrypted as it’s read. This process can be done with minimal impact on speed (thanks to a dedicated processor), so that you know your information is safe without having to think about it.

Adata SD700 Waterproof SSD
The Adata SD700 Waterproof SSD.


External SSDs can be purchased with a waterproof rating, which can be either small splashes or actually able to be fully immersed in water, even for days!

This is a great choice for anyone who uses a laptop in the field or is worried about potential flooding. The actual depth rating should be given on the device statistics.


This refers to an SSD being sealed against dust entering the casing and causing damage. This is typical of external models. For the best proofing, look for products that give details of what standard they are tested to, such as IP68.


You can buy external drives with shockproof casing, which is ideal if you’re worried about dropping the device. Again, this is perfect if you have to take your data on field trips or just regularly transport the drive. Ideally, look for a military standard.

Energy Efficiency

Most SSD drives are very efficient, certainly compared to mechanical HDDs. If this is a concern, look for drives that specifically mention energy efficiency or green ratings, as some are designed specifically with this benefit in mind.

USB 3.0 Cable

Connection Type

The main two connection types are the SATA cable for internal drives and USB cable for external drives. You may come across firewire variants for external drives, which is just as suitable, but for the best speeds USB 3.0 is recommended – make sure that your motherboard supports this first.

Auto Backup

SSD drives can be purchased with an automatic backup system, usually via bundled software. This is a great way to protect your data without any extra effort. The software will regularly copy important files to another drive on your PC, operating in the background to avoid getting in the way. This means that you’re always prepared for the worst.


Internal drives tend to be all one size, 2.5”. The size and shape of these drives is fairly universal, though again some can be bought in the PCIe configuration, which will be quite small, having no casing. External drives are a little bigger as they need a protective shell – the more protection, the bigger and heavier the case.

Software Included

Bundled software can range from auto-backup programs to special programs for disk health checking, encryption and data management. While these programs are rarely essential, they do add value to your purchase, so it’s worth checking them out.


A warranty is a great thing to have for any storage, as you never really know when things can go wrong. A 1, 2 or 3 year warranty is pretty standard now for most reputable brands, so balance this with the cost of the device. More peace of mind is always a plus.