Samsung QVO vs EVO: Which is Better?

If you’re shopping for a new SSD, be prepared to encounter a lot of flash-memory jargon: TBW, 3D NAND, SLC, QLC, DRAM, IOPS, and more. Additionally, companies like Samsung use labels like EVO, QVO, and PRO to differentiate between their SSD lineups.

So, what exactly is the difference between an EVO SSD and a QVO SSD? Let’s find out in this guide.

SSD Basics

SSDs store data in flash memory chips, more specifically NAND flash. Inside these flash chips are billions of small memory cells arranged in a vertically stacked arrangement, commonly known as 3D NAND or V-NAND. A cell is the smallest unit of an SSD.

↪ Cell Types

Cells store data by trapping electrons or charges. The market is filled with four different types of cells. The underlying physics is quite complicated, so we won’t dive into the details of their construction.

• SLC (Single Level Cell) – Stores 1 bit per cell | High Speeds | Costly
• MLC (Multi Level Cell) – Stores 2 bits per cell | Slightly Lower Speeds | Less Expensive
• TLC (Triple Level Cell) – Stores 3 bits per cell | Lower Speeds | Cheaper
• QLC (Quad Level Cell) – Stores 4 bits per cell | Slowest Speeds | Cheapest

For example, if you wish to store “255” (11111111 in binary) in a QLC SSD, you might only need a part of a single cell since QLC cells can store up to 4 bits (16 different states) each. However, an SLC SSD would require eight cells because each cell stores just one bit. It’s important to note that this simplification ignores complexities such as wear leveling, error correction, and actual write amplification which affect how data is physically laid out in the SSD.

↪ TBW (TeraBytes Written)

The endurance of SSDs is measured in TBW or TeraBytes Written. Once this value is exceeded, data cannot be stored reliably. Reading data from SSDs is less taxing on the lifespan compared to writing, but very high-read scenarios can still contribute to wear through mechanisms like wear leveling and background activities. However, this impact is minor compared to the effect of write operations.

↪ Read/Write Speeds

The term “Sequential Read/Write” represents the speed you should expect from your SSD when reading from or writing to files that are placed next to each other.

Random Read/Write speeds are expressed in IOPS (Input Output Operations per Second). These speeds indicate how quickly data can be read from or written to randomly. Higher speeds can improve day-to-day usage and fluidity.

↪ SLC Caching

Most buffering on your SSD is done through a process called “SLC Caching.” A small part of your SSD is converted to fast SLC and acts as a cache. Writing data directly to QLC SSDs is slow, so manufacturers convert a part of your SSD into SLC Cache to speed up the process.

This was a basic rundown of the terminologies we will focus on later. For a very in-depth guide regarding SSDs, we suggest you read to read our detailed SSD Buying Guide.

EVO vs QVO

Initially, Samsung only offered PRO and EVO SSDs. However, this changed in 2020 when Samsung introduced its first QLC offerings. QLC is intended to offer higher capacities, but the tradeoff is reduced speed and lifespan.

For context, here is a comparison of Samsung’s 860 series, which launched in QVO, EVO, and PRO variants. Let’s go over the primary differences.

1) NAND Type

Samsung’s QVO SSDs are cheaper and denser since they use QLC memory. Meanwhile, the EVO lineup is equipped with slightly better TLC, and the PRO series uses MLC. SLC is reserved for military-grade and enterprise-level equipment due to its cost.

Raw QLC performance can be slower than that of hard drives and flash drives once the SLC cache fills up. QLC stores 4 bits per cell, resulting in 16 different voltage thresholds or possible values that can be stored.

Samsung rates the raw speeds (once the SLC cache is exhausted) for the 870 EVO at 530 MB/s. The 870 QVO can slow down significantly once its SLC cache is exhausted, sometimes reaching as low as 80 MB/s under certain conditions.

However, it’s essential to note that the actual slowdown can vary based on workload and firmware optimizations. Some lower-end HDDs might have sequential write speeds comparable to or even lower than a QLC SSD operating without cache.

2) Lifespan

The Samsung 860 EVO 1TB has a TBW of 600 TeraBytes Written, while its QVO counterpart has just 360 TBW. If you write 50GB/day, here’s the average lifespan of both drives:

1. Samsung 860 EVO – 32 Years
2. Samsung 860 QVO – 20 Years

That’s a significant decrease. Why? QLC SSDs need to distinguish 16 different voltage levels, twice as many as TLC. Consequently, QLC cells undergo increased degradation compared to TLC cells. This is due to the higher number of voltage levels required to store 4 bits per cell (16 levels for QLC) versus 3 bits per cell (8 levels for TLC). The tighter voltage tolerances lead to higher error rates and faster wear over time.

3) Storage Capacity

The Samsung 870 QVO offers up to 8TB of storage, whereas the 870 EVO tops out at 4TB. A QLC cell can hold 4 bits, but a TLC cell can only store 3 bits, allowing QVO SSDs to store 33% more data with the same number of cells.

1. Samsung 870 EVO: 250GB, 500GB, 1TB, 2TB, and 4TB
2. Samsung 870 QVO: 1TB, 2TB, 4TB, and 8TB

4) Price

SSD prices vary over time. At launch, the 870 QVO was actually more expensive than the 870 EVO by $20. However, SSD prices can fluctuate rapidly.

1. Samsung 870 QVO 4TB Launch Price: $500
2. Samsung 870 EVO 4TB Launch Price: $480

Nowadays, the 870 4TB EVO is 10% more expensive than its QVO counterpart. Given this price difference, it’s important to consider the trade-offs in speed and TBW before making a choice.

So, which SSD is for you?

The most recent QVO SSD from Samsung is the Samsung 870 QVO, launched in 2020. Due to the marginal price difference with its EVO equivalent, it typically makes sense to go for the Samsung 870 EVO.

However, in a general sense, QLC SSDs aren’t inherently bad if you’re using them for read-only purposes. If you want to use it as a game drive or a Plex drive, you probably wouldn’t mind the drawbacks of QLC.

For your operating system, longevity and sustained write speeds make TLC (EVO) equipped SSDs a better option. The choice is yours.