Different Types of PC Storage Devices

Different types of PC storage devices

HDD, SSD and M.2 NVMe drives are used to store data. It’s the persistent memory in your computer, this means that the data is retained even when the power is lost.

You probably have heard people talking about HDD and SSD drives, maybe even about M.2 NVMe drives, but you don’t know the difference between them. In this post, I will cover the basic knowledge about these drives and what to keep in mind when buying them. You will notice that the abbreviations easily make these simple things sound a lot more complicated than they are.

I will first cover basic information about HDDs and SSDs, and then I will go through some of the advantages and disadvantages between them. Hybrid drives and M.2 NVMe drives are explained last since they have some differences compared to HDDs and SSDs.


HDD means Hard Disk Drive, it’s the oldest of these three storage drive types. The name refers to the actual magnetic disk that stores the data. The data is then written and read from the disk with a magnetic head. Hard disk drives are still very commonly used in computers. In desktops the size of an HDD drive is usually 3.5” and in laptops 2.5” and the capacity varies depending on the computers age.

I don’t recommend buying HDD with less than 1TB of storage, because the prices HDDs are sold are so low, you can get 2TB hard disk drive for almost the same price. 2TB should be enough storage for most users.

As mentioned earlier, HDDs are placed in the 3.5” slots in your case. If you are planning to have more than one or two HDDs, make sure that your case has enough slots for your drives. Most cases have at least two 3.5” slots.

HDD connectors

Modern hard disk drives are connected with SATA III cables, which have L-shaped connectors. You have to plug in SATA cable for data and another SATA cable for power. The wider SATA is for power and another one is for data. The SATA cables can be plugged in only one way, you can’t plug them in incorrectly. You can also use MOLEX cable to power the drive, but I usually just use the SATA cables. You can read more about the speeds of SATA cables from my post about motherboards.

Older hard disk drives used IDE connectors. If you see someone selling a drive with IDE, just don’t buy it, it’s old technology and we want to get the best performance for our money.

Hard disk drive with SATA and MOLEX connectors

Hard disk drive with SATA and MOLEX connectors.


HDD cache/buffer

Hard disk drives have cache or buffer, which works as a temporary memory for the drive. It helps the drive to multitask, it is very useful in servers. The bigger the cache, the more data it can simply store in the cache. However, the amount of cache isn’t very important for the consumer to worry about, it’s just a good thing to know what it is for. Sometimes it might help selecting between two otherwise similar drives.

The cache also makes the drive faster, because it is storing the data that is most frequently used by the user and programs. This makes the HDD faster because it doesn’t have to pull the data out of the disk every time, it can just access the cache and read it from there.


SSD means Solid-State Drive, it is a newer storage type. There are no moving parts inside the drive, unlike in HDDs. This makes solid-state drives more durable than hard disk drives. In SSDs the data is stored in flash memory chips. Flash memory is used in USB drives as well, but the type is different, SSDs flash memory is more reliable and faster. Solid-state drives for computers fit the 2.5” slots, many laptops use the same sized SSDs. However, some laptops might have even M.2 NVMe drives to save space and make it faster.

Many systems have both HDD and SSD, this setup saves money if you would otherwise just buy a big SSD, and it speeds up your system. In this kind of setups, solid-state drives are commonly used to store the operating system and most commonly used applications. All the other data can be stored in the HDD, this makes booting up your system and launching your most used programs faster.

If you are planning on doing HDD and SSD setup, I suggest getting at least 250GB SSD and 2TB HDD. This, of course, depends a lot on your needs, but with these sizes, you aren’t running out of storage.

SanDisk solid-state drive

SanDisk solid-state drive.


SSD connectors

Solid-state drives are connected with SATA cables. Just like with hard disk drives, you need SATA power and SATA data cables to have the drive working in your system.

SSD cache/buffer

Solid-state drives usually have the cache as well, this is almost the same thing as with hard disk drives. The cache in SSDs is DRAM, it is very fast and can keep up with the speed of the SSD. Not all SSDs have cache.

Advantages and disadvantages between HDDs and SSDs

One of the biggest advantages hard disk drives have compared to solid-state drives is the price. SSDs are more expensive and they are predicted to be more expensive than HDDs for some time. The amount of capacity the drives have is associated with the price of the drive. Hard disk drives are usually sold with higher capacity than solid-state drives. HDD is cheaper and has usually more capacity than SSD because of that.

Another big difference between these drive types is the speed they can read and write. SSD is faster compared to HDD and this is why it is so popular nowadays. I mentioned the use of SSD and HDD in your system to achieve the best results for the price earlier, SSD should store all the most often accessed data.

Hard disk drives have a longer lifespan than solid-state drives. SSD shouldn’t be used for archiving data, because they will start losing data if they are left long times (1-2 years) without power. Keep your SSD connected and in use. Although HDD is better for archiving, it is more fragile to impacts than SSD. This is because the HDD has moving components inside it and SSD doesn’t.

Hard disk drives produce noise, because there is a write and read head moving back and forth. SSD is completely silent since it doesn’t have any mechanical components in it.

Lastly, SSDs consumes less power than HDDs.


As you can see, hard disk drives have fewer advantages compared to solid-state drives. That said, it might be a good idea to invest in an SSD if you want to build a modern computer. Many people, including myself, buy HDD and SSD for their new computers. This allows you to place the operating system in the SSD, which makes your computer boot very fast.

You can also move your most used games and programs to the SSD if you have big enough SSD. This allows you to start them faster as well. The HDD is used as a file storage and for anything you don’t use that often. This is how you can save some money and still have a fast operating system and enjoy the faster launches of your most used programs and games. When you buy SSD and HDD for your system, you can buy smaller SSD where you can fit all you need to. This way you can spend more on a larger HDD for all the rest data. I usually go for 250GB SSD and a 2TB or bigger HDD in my builds.

Hybrid Drives

There are also storage drives called hybrid drives, this kind of drives combine features from both SSDs and HDDs. Two main technologies are dual-drive hybrid systems and solid-state hybrid drives (SSHD).

Dual-drive hybrid systems are simply systems that have separate HDD and SSD. This is very common setup, as I have mentioned earlier I make this kind of builds myself. It is also possible to combine the two drives to one drive by a software, this makes the setup look cleaner for the user since the drives show as one drive.

SSHD or solid-state hybrid drive is a product that combines SSD and HDD. It’s a single device with both drive types. It offers the same benefit than the dual-drive hybrid system but in one device. SSHD isn’t very popular, but they are available if you want to give it a try. Personally, I use separate SSD and HDD (dual drive hybrid system).

M.2 NVMe drives

M.2 drives are also solid-state drives (SSD), this means that they are faster than hard disk drives (HDD). The difference to common SSDs is that M.2 drives are a lot faster than normal SSDs attached with SATA cables. This is possible because the M.2 drives are connected directly to the motherboard. M.2 drives replaced the mSATA drives, which were also connected directly to the motherboard.

To be clear, M.2 is the connection type, modern M.2 connectors include PCIe 3.0, SATA 3.0 and USB 3.0 in the connector. Since it is connected into a PCIe slot, the protocols to transfer data are AHCI and NVMe. From these two protocols, NVMe is more used and the drives are often also called as M.2 NVMe drives.

M.2 NVMe drives offer very high speed, modern M.2 drives connected into the PCIe slots are able to offer speeds as high as 32.0 Gb/s. However, that is the theoretical speed and the real speed will be lower. M.2 drives are great if you want to achieve high speeds and reduce boot and launch times. The speed also varies if you write or read from the drive.

120GB M.2 solid-state drive

120GB M.2 solid-state drive.


External Drives

External drives are a very common way to store data, that you don’t need all the time. They are often also used to backup data or as an additional storage to a laptop. Nowadays, cloud services help a lot with keeping recent backups. External drives are still very useful as a cold storage. Cold storage is a storage that is not connected to a device or used anyway, it is a great way to secure sensitive data from getting stolen or to prevent corruption. If you are using a password manager, you should keep a copy of the encrypted file in a cold storage.

HDDs work very well as a cold storage since they don’t start losing data when being long times without power like SSDs do. Hard disk drives are also cheaper, and you don’t usually need the external drive to be very fast. I’m using a 3TB external hard disk drive as a backup storage, it is most of the time unused, so it is an cold storage.

Keeping backups is a very important thing. You don’t want to lose your files and pictures. Backups are easy to manage, and they really save you if your HDD or SSD totally corrupt. Storing backups on a frequent basis is a good habit to start doing regularly.

Security features

Another important thing is security. Encrypting your drives is a simple way to improve your security. Encrypting is easy to do when your system is new and drives are still pretty much empty. If the drive is filled with files, it will take a long time to encrypt the drive. So, if you want to enhance your security by encrypting your drives, I suggest that you do it when you take your new system into use.

If you have Windows 10 Professional, Education, Enterprise or Windows 7 Ultimate, you can use BitLocker. To have the best security with BitLocker your motherboard needs to have Trusted Platform Module (TPM). However, it is possible to use BitLocker without TPM, it just isn’t as secure as with TPM.

You can also use VeraCrypt or DiskCryptor to encrypt your drive if you are running the Home edition of Windows. VeraCrypt works on Windows, Mac OS X, and Linux-systems, but it is only able to encrypt whole drives in Windows systems. Remember to use strong passwords when encrypting your files, folders, and drives.



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PC Rookies is a project to share information related to mostly security related topics.

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