The Ultimate Guide to SSDs: Types and Differences Unveiled

Choosing an SSD involves more than just capacity and price; there are other crucial factors to consider. Let's delve deeper into this storage device in today's ultimate guide to building an affordable PC.

In today's tech landscape, SSDs have become extremely popular, emerging as the top choice for PC enthusiasts whether for work or gaming. When upgrading systems, opting for an SSD over an HDD is a common consideration, emphasizing the importance of selecting the right SSD.

Classification by Format

When purchasing an SSD, the first thing to know is which format your computer supports. While the most common SSD standards are M.2 and 2.5-inch, there are two other lesser-known types of SSDs worth exploring.

2.5-inch SSDs

The Most Common and Easy-to-Install Format for Any PC or Laptop

This is the new format that has been increasingly popular in recent years, with a size just larger than a stick of chewing gum. However, to use this type of SSD, you need a motherboard equipped with an M.2 slot. Most modern motherboards have one M.2 slot, while some have two. Additionally, M.2 SSDs come in various lengths.

mSATA SSDs

This abbreviation stands for Mini SATA. These SSDs look quite similar to M.2 SSDs and are designed for use in devices with limited space.

U.2 SSDs

This format doesn't differ much from the 2.5-inch SSD, but it's slightly thicker. It doesn't use the SATA connection but rather PCIe with very high speeds. These types of drives are equipped for high-end workstations, servers, or supercomputing systems requiring large capacity, high speed, and durability.

Learn more: What are HDD and SSD, and how are they different

Two Types of SSD Memory Chips

Regardless of the format, all SSDs store data on flash memory chips. There are various types of memory chips, with noticeable differences in speed and durability. Choosing an SSD that uses the right type of memory chip to meet your needs can save you a significant amount of money in the long run.

• NOR Chip: The advantage of NOR chips is high-speed random data access. However, NOR chip production costs are higher and capacities are lower, so they're usually limited to electronic devices for storing code. NOR chips can be found in medical devices and smart devices.
• NAND Chip: Compared to NOR chips, NAND chips excel in sequential data access, fast read/erase/write operations, and lower costs. Therefore, NAND chips are commonly used in consumer SSDs or large organizational data storage. NAND chips can be found in memory cards, USB drives, smartphones, SSDs, etc.

Four Types of NAND Chips in SSDs

Due to its cost-effectiveness and high capacity, NAND chips are commonly used in computer devices. The majority of SSDs on the market utilize this type of memory chip to balance price and capacity. However, they are further divided into smaller types, each with its own pros and cons.

• NAND SLC: SLC stands for 'single-level cell,' indicating that each memory cell of the chip stores only 1 bit of data. This ensures very high speed and durability but comes at a high cost.
• NAND MLC: Short for 'multi-level cell,' it has memory cells that store 2 bits of data. This type of memory chip still offers high speed and durability but at a reduced cost.
• NAND TLC: With each memory cell storing 3 bits of data, it's called triple-level cell. Increasing data density helps reduce costs and increase capacity, but it also decreases durability.
• NAND QLC: Known as 'quad-level cell,' each memory cell of this chip holds 4 bits of data. It's the cheapest type among NAND chips but offers the highest capacity.

Additionally, you may have heard of 3D NAND, where memory cells are stacked on top of each other to increase SSD capacity. This solution aims to increase capacity and reduce costs without shrinking memory cells too much, which could compromise reliability. It's an initiative that enables the production of high-speed, high-capacity SSDs, albeit at a considerable cost.

For regular users, SSDs using NAND TLC and QLC chips are sufficient to meet their needs. For example, SAMSUNG produces three different SSD lines: Pro, EVO, and QVO. Among them, the Pro standard SSDs have the highest price with MLC NAND chips, EVO SSDs are equipped with TLC chips, and finally, QVO SSDs use QLC chips.

TLC and QLC

As these are the two most common chip types in SSDs for ordinary consumers, Mytour would like to elaborate on them in this section.

Capacity

QLC chips have a significant advantage in capacity due to higher data density. You can find QLC SSDs up to 8TB, although their prices also exceed tens of millions. Meanwhile, TLC SSDs have a lower capacity.

Durability

QLC chips have higher data density and therefore are more prone to damage. The lifespan of SSDs is measured in TBW (terabytes written). Referring back to the example of Samsung's EVO and QVO lines above, a 1TB EVO has a durability of 600 TBW while a 1TB QVO is only 360 TBW.

Of course, these numbers are for reference only and indicate that the product is still under warranty. SSDs can still fail unexpectedly even before reaching TBW, or they can last much longer than the announced TBW.

Performance

Super-fast read-write speeds are what users desire when using an SSD. It's easy to guess that drives using QLC chips will be slower compared to TLC (or other drives using different NAND memory types). Manufacturers sometimes use software solutions to minimize this difference, for instance, Samsung's Intelligent TurboWrite helps their QLC drives achieve speeds comparable to TLC drives in the first 42GB.

Cost

As Mytour mentioned earlier, SSDs using QLC chips are cheaper compared to TLC, MLC, or SLC drives of the same capacity. This is a significant factor in the storage solution choice for ordinary users. However, if you need a drive for professional gaming or 3D rendering, SSDs using high-end memory chips will be a much better choice.