What is an SSD and why would I want one?

SSD (Image credit: Windows Central)

Update March 13, 2017: We've refreshed this article with some new resources and more information on swapping out your old drive with a new solid-state drive.

Many Windows PC users wade into the solid-state drive (SSD) market without the knowledge needed to make an informed buying choice. We take a look at solid-state drives and what's inside them to help prepare you for your next storage device.

What is a solid-state drive?

When you get down to a base level, an SSD is just some memory chips on a circuit board. It has an In/Out interface, usually in the form of SATA or PCIe, that feeds power and transfers data.

Unlike traditional hard-disk drives (HDD), there is no actuator arm that has to move across a spinning magnetic platter to read or write data. In fact, there are no moving parts at all. Most SSDs instead use NAND flash memory, which is relatively stable and will last for years.

Why use a solid-state drive?

There are a number of reasons why you might want to opt for an SSD in place of a standard HDD.

Laptops can take a beating while they travel with you — having a storage device that isn't disrupted by bumps is a huge boon. HDDs with their moving parts can be damaged if they're spinning when the drop or impact happens. SSDs are far less likely to be affected by impacts.

Mobility is a huge part of laptops; SSDs are both smaller and lighter than HDDs. This saves space to include other hardware in the laptop and reduces weight and thickness. SSDs also require less power, so your laptop battery should last longer.

Most people who've been using Windows for years know how long boot times can be when using an HDD. Differences in speed loading apps on your PC might be minimal — you probably won't notice if Office apps load in two seconds rather than four — but using an SSD to boot Windows 10 will significantly cut time spent twiddling your thumbs.

On top of all these perks, SSDs also have a way lower failure rate than HDDs. If you're backing up important data, it's never a bad idea to save it on an SSD.

Choosing the right type of memory

There are three types of memory that you should look out for when buying an SSD:

  • Single-level cell (SLC): These cells can each hold one bit of data — either a 1 or a 0. There are thus only two possible values that can be read from each cell.For this reason, SLC memory is the fastest and most precise when it comes to writing, takes the least amount of power, and will last the longest.The trade-off is that it is also the most expensive. SLC solid-state drives are typically used in an enterprise scenario because of their price but are available to everyone.
  • Multi-level cell (MLC): These cells can each hold two bits of data per cell — a 1 and a 0. Because it can hold both bits, there are four possible values: 00, 11, 01, and 10.MLC memory can thus have a larger amount of storage without physical size increasing, are available for a cheaper price, but have slower and less precise write speeds. They also use more power and wear out about 10 times faster than SLC memory because of the increased power use.Keep in mind we're not talking about longevity in months or years — we're talking about decades. By the time most SSDs wear out they'll likely be long-outdated by whatever storage technology comes next. MLC solid-state drives are your standard drives found in most high-end devices today.
  • Triple-level cell (TLC): These cells can each hold three bits of data per cell, and are available in big storage sizes at a decent price. The tradeoff is a slower read and write speed and less precision, as well as reduced longevity thanks to increased power consumption.

Understanding NAND memory chips

Negative-AND (NAND) memory chips are what house your SLC, MLC, or TLC memory cells. When SSDs first emerged on the market, most cheap models had about five NAND chips in them, while expensive models had up to 10 NAND chips.

Now current technology allows for way more NAND chips and way more storage. Vertical NAND (V-NAND), a relatively new approach, stacks cells on top of each other — cells retain the same performance because they're not all cramped together, and you can have large storage sizes without large physical sizes. For example, a single 48-layer V-NAND chip can hold 32GB, so in a 4TB SSD (opens in new tab), you would have 125 separate NAND chips.

All NAND memory has something called error-correcting code (ECC) built in. This is designed to fix any errors that occur as data is written and read on your SSD; your cells will continue working properly, and the overall health of your SSD will be maintained.

Choosing the right connection

When it comes to in/out interfaces — what you connect the SSD to your motherboard with — there are a few common options to choose from.

  • SATA III: Serial ATA (SATA) III technology came about back in 2009 and is still used today in many SSDs. Read and write speeds on an SSD connected with SATA III will hit about 600MB per second. SATA was fine for HDDs but limits many SSDs.
  • PCIe: Peripheral Component Interconnect Express (PCIe) solid-state drives bypass SATA connections and plug right into a PCIe lane in your motherboard. While PCIe solid-state drives are much more expensive (opens in new tab), they also transfer data much faster — write speeds can surpass 1GB per second.
  • M.2: Most common in laptops and all-in-one PCs, M.2 SSDs are physically smaller without sacrificing storage space. They are available in both SATA III and PCIe variants, depending on which your device supports.
  • NVMe: Non-Volatile Memory Express (NVMe) technology is relatively new — it was designed specifically for SSDs and the problems they faced using SATA connections. NVMe is designed to maximize the amount or requests sent to an SSD, as well as making it possible to receive requests from multiple processor cores at a time.What does this mean for you? Real results will show up in enterprise-sized servers, but you might notice your PC is suddenly able to load apps instantaneously. NVMe solid-state drives come in either PCIe or M.2 formats to fit both desktops and laptops.

Choosing a solid-state drive

Now that you've read through the guide, you can go about choosing an appropriate solid-state drive for your desktop or laptop.

The sweet spot for most people is probably an MLC solid-state drive with a SATA III connection in their desktop, while most people will enjoy the same in their laptop, albeit with an M.2 connection.

If you'd like an idea of where to start, we've put together a great SSD buyer's guide to get you on your way.

See the best SSD available now

Upgrading to a solid-state drive

Use Macrium Reflect to clone your hard drive (Image credit: Windows Central)

If you have a solid-state drive in-hand and are ready to swap it out in place of your old hard drive, you're probably wondering where to start.

Good news: you don't have to start over fresh. Using a tool like Macrium Reflect or Acronis True Image (opens in new tab) — there are plenty of other options out there — you can clone your old hard drive over to your new solid-state drive. Once you swap out the drives, everything will be just as you left it, but you'll be enjoying the speed and reliability of the SSD.

The process of cloning your hard drive might seem a bit daunting for anyone who hasn't done it before, but we created an in-depth guide to get your through safely.

Complete guide to cloning your hard drive with Macrium Reflect

We've also created specific guides on upgrading to an SSD in the Dell XPS 13, XPS 15, and the Razer Blade.

Cale Hunt
Senior Editor, Laptop Reviews

Cale Hunt is formerly a Senior Editor at Windows Central. He focuses mainly on laptop reviews, news, and accessory coverage. He's been reviewing laptops and accessories full-time since 2016, with hundreds of reviews published for Windows Central. He is an avid PC gamer and multi-platform user, and spends most of his time either tinkering with or writing about tech.

  • Great article, Cale !!
  • For desktop the right choice today is Samsung EVO 850 with 500GB, in my opinion. Ultra fast, 130€ shipped.
  • That's the same one I use in my daily laptop which is about 4 years old now, it's well worth the money
  • I use Samsung 950 PRO, but that's me ;)
  • I was talking about the best quality/price but your e-penis is very long :D
  • Me too. 256GB. Fastest sucker out there. I go from bios post screen to desktop in less than 10 seconds. Gotta love that - too bad I almost never have to reboot ;)
  • I use the 960 evo.
  • I am with Dainel here.  The Samsung 950 PRO​ performace hand down better then the EVO 850.  I have used three Crucail products and they all had issues.  Crucial solution, update the firmware.  Never a problem with the Samsung devices.  
  • Factor in the price versus the daily needs, obviously if you do heavy file processing there are better solutions but in that case you usually don't need a tutorial article either!
  • I have a Samsung 850 PRO 1TB in my build, never have any problems with Samsung SSDs
  • If you have M.2 and just use it for light browsing, email, light gaming, etc, Intel 600p is an interesting look. :) About 60% of the cost of the 950 Pro (which is the better choice if you have the money). ​If you put it under heavy, heavy work loads then it can get bogged down. But for most users not doing mass video editing, its a snappy drive :)
  • Vow, great info....
  • That "MixRadio" sticker on the PC thou :'(
  • I miss MixRadio
  • I hard reset my 925 today, and this was one of preinstalled apps. Store couldn't update this and few other of 30+ apps
  • Wish I'd understood this before I bought my last desktop. Will certainly consider it for next laptop. Thanks for the excellent info. Even a novice like me could understand it. :)
  • You can change it without reinstalling windows, did it the other day. Bit2bit clone and then swap the drives.
  • Is that wise? Performance wise?
  • Don't hesitate to add a SSD to your computer. It's the most significant upgrade I've bought for a computer in 30 years.
  • 100% agree
  • For internet browsing and general computing stuff I agree. If its a gaming desktop the SSD wont do a whole lot for you. A better GPU or faster RAM would probably be better than an ssd for games.   But I will say, its the most noticable difference. A computer starting in 20-30 seconds is much better than one start in 1-2 minutes, lol :). But if you have that stuff then get an ssd and install your games on a hdd like the last few days tutorials have instructed and rock the 30 second boot times! (30 seconds means steam, battle net, keyboard drivers, everything loads in that time).
  • At work, our contribution to the "new PC sales slump": We've had great success replacing old HDDs with SSDs in 3-4 year old equipment. SSD + Ram boost to 8GB + Win10 = a very good PC for $150 - 250. Posted via the Windows Central App for Android
  • Everyone who has an old laptop that they still plan on using should add an SSD to it. My old HP Probook was extremely slow especially on bootup and it was becoming really annoying. I bought the cheapest SSD i could find and moved the OS on it and my laptop was REBORN! I cant begin to describe how much faster the laptop is, it feels like a new machine. If you have 60$ to spare for a cheap SSD its the best thing you can do to keep your laptop fresh and working and the same goes for your PC.
  • I first read the headline as "What is an STD and why would I want one?"  I have two goals today: obtain coffee & get an eye exam.
  • Lol
  • Nice article, Well Put. Thanks
  • I've spent my entire life avoiding STDs! SSD is too close so I will also avoid that...
  • Really informative article and well written. I need to save this one for future reference.
  • Awesome article. Very useful information. Saved already.
  • How would you know this SSD is a SLC or MLC or TLC?
  • If you're buying a new SSD, the manufacturer will generally specify if it's MLC, TLC, or SLC. If the SSD is already in your PC, quickest way to find out is to Bing the model number on the SSD ;)
  • This made my day, thanks. I've been wondering to get one for my desktop PC.
  • I dunno if I wanna be reading a article about SSDs from windowscentral....they're kinda novices.....Its kinda like asking a football jock for advice on how to change your car's oil....
  • Then don't read it.  Personally, the article was very informative for me.  I don't need (and wouldn't want) an article filled with more technical stuff I wouldnt understand and would need another article for.
  • I agree. About a month or so ago I built a new desktop PC and used WindowsCentral for a LOT of information of what to plan for and just educating myself about newer technology as it's been at least a decade since the last time I built a PC. WindowCentral is GREAT at explaining things for the lay-person like myself that is NOT a tech-minded person as I have a differnt vocation calling in my life and need a good source for helping me to become educated on topics and help me to make decisions. Super tech people may read some of the articles and think, "Anybody should already KNOW this!", but not everybody IS a tech-savy person. I sincerely appreciate how WindowsCentral presents articles that even a Horticulturist like myself can understand and become educated by. Thank you WindowsCentral, and if you have any Horticulture-related questions, please feel free to send me a message.
  • Upgrading to a SSD is the single biggest way to improve slow performance I reckon. Posted via the Windows Central App for Android
  • I have the 1TB Toshiba OCZ RD400 M.2. Love the speed.
  • I have a six year old HP Elitebook laptop and I first changed the HDD to a 128GB Crucial SSD. And after that it's been like Christmas every day.
    Last year I changed it to the 256GB Samsung 850 Pro and it's just great. And as it had it's own cloning program, it was a painless operation. I just can't understand why would anyone still be using a HDD as the only storage anymore! It's like trying to drive a Tesla with steam.
  • Still runing this setup. The battery has died so it just sits in the docking station. The fan is noisy and the machine runs quite hot.
    I guess I have to start looking for a placement.
  • SSD is one of the best things ever made for pc since awhile, they read 12 times faster than a normal 7200rpm HDD !! Samsung Evo are excellent choice but they are expensive if you want a good SSD look for Kingston HyperX Fury or HyperX Savage, they are reliable and cost half the price, i also install some SSD from ADATA in some build and i never got any problems with them... Those i have the most problems with are Crucial, Patriot and Kingston V300 series !! Im talking about SATA drive...
  • Strange that Crucial have problems, considering their DDR memory chips are the most reliable ones I've ever used
  • Good lookin out.  Thanks.
  • I have one of the Crucial V300 SSD drives and so far have had no problems. Granted, I've only had it for about a month, but so far so good.
  • Its Sandisk all the way for me, never had an issue with any of their SSD's.
  • Samsung for me, my 850 Pro has had several TB of writes and still going well. The Samsung drive software shows the status as 'good'
  • Windows Central is fast becoming its own ArsTechnica/Toms Hardware. Real tech stuff.  I like it!
  • You should spend less time explaining the maximum speeds (sequential) since that was never the problem with mechanical drives. The benefit SSD's bring is that mechanical hard disks (no mater how fast they spin or how they are connected) can only get a few MB/s random reads/writes and the read latency is abysmal - up to 20ms per operation. Most good hard drives top out at about 150 iops (input/output operations per second). SSDs have no moving parts, so there's no mechanical latency. Random read and write speeds are easily in the hundreds/thousands of MB/s, with IOPS figures way above 100,000. *That's* where ssd performance is killer, random reads and writes are the bane of existence with hard disks. No more defragmenting to reduce mechanical latency. Hurrah! Here's an example from my system. HDD is Seagate 2TB ST2000DM1 drive. SSD is 500GB Samsung SM 941 (AHCI, not NVME) on M.2. Using the built in Windows system performance tool Winsat. HDD:  Disk  Random 16.0 Read 1.00 MB/s, Disk  Random 16.0 Write 1.00 MB/s SSD:  Disk  Random 16.0 Read 1060.04 MB/s, Disk  Random 16.0 Write 790.47 MB/s
  • But the Cost factor is high for a regular office and home users Till Now.
    When the cost of SSD will decrease , then some new SD(storage device) will be in the market .
  • The question that immediately comes to mind is "What's the downside?" When my mechanical HDD is ready to be recycled, is there any reason why I wouldn't replace it with a SSD?
  • The downside is cost per gigabyte. If you have a LOT of media and static storage needs (games with large,m compressed assets for example), you'll not really see the benefits of ssd technology. You should definitely try to have your OS on a an SSD, but if you mainly have your pc for media consumption and gaming you'd be well served by buying a smaller ssd -250GB or so - and a large hard disk (a few in the 2-4tb range, or a large oen if you dont mind data redundancy). Really up to you. If/when ssd tech gets to the same price per gigabyte as hard drives, there'll be no reason to continue using anything else, even for static storage.
  • Samsung 850 PRO here. My next pc upgrade will involve an Nvme drive
  • The price of these SSDs is too damn high!
  • Your comment needs THIS guy!
  • Darn! The photo isn't showing up. I linked in a photo of the "The Rent is too Damn High!" guy!
  • Now they are very cheap sh.t!  Do not look for 16TP or 60TP!    
  • I first read the headline as "What is an STD and why would I want one?" and thought this was perfect timing considering Spring Break is near approaching. Oh well.
  • Ha! Ya gotta love those mental Freudian slips!
  • One of the best updates for my computer is a SSD, I  got myhself a Corsair force 3 128Gb Sata first of all, I loved it, but decided after 12 months to go with something a bit larger and slightly faster, so I went for a Corsair 240GB Neutron drive, again Sata. when i update this machine to a Ryzen, I will get a board that have m.2 PCI-E connection and eventually I will get a drive to fit it when they come down in price a bit, no doubt another Corsair.  
  • Why WC keep piggy back the new articles over the old ones?!!
    This is bad journalism. Not only forces you to read the entire article again, it wonders you what is the addition to the old writing since the update language is not distinguishable from the old one!
  • What is this, the 5th article with a different title about SSD drives????
  • Great article, C. Hunt !!! Apart from this, is there any gadget/protector case for laptop which decreases the bump effect of laptop HDD while traveling??
  • Currently rocking the Samsung 960 Evo 1Tb in my desktop pc. Love it.
  • "Negative-AND"?? WTF? Someone needs to brush up on some CompE basics here...
  • Is it possible to add a SSD beside a HDD in a laptop like Acer E5 series?