In-depth Analysis Of Solid-State Drives (SSDs): From Flash Memory Chips To Protocols, A Must-Read To Avoid Pitfalls

Solid-state drives (SSDs) have now become a standard component for building or upgrading a PC. However, prices on the market vary widely, ranging from just a hundred yuan to over a thousand yuan. Many consumers make impulsive purchases only to encounter issues like slowdowns, lagging, and short lifespans.

In reality, the performance and longevity of an SSD depend on three core factors: flash memory chips, protocols, and controllers. This article breaks down the essential knowledge of SSDs to help you make informed choices and avoid common mistakes.

Flash memory chips serve as the storage units of an SSD, and there are four main types, ranked by quality from highest to lowest:

1. SLC (Single-Level Cell): Stores one bit of data per cell. It delivers the fastest speeds and longest lifespan but comes at an extremely high cost. It is exclusively used in enterprise-grade SSDs and is nearly unavailable in the consumer market.
2. MLC (Multi-Level Cell): Stores two bits per cell. It offers a balanced mix of performance and durability, once the top choice for high-end consumer SSDs, but has been gradually discontinued due to high production costs.
3. TLC (Triple-Level Cell): Stores three bits per cell. Currently the mainstream option for consumer SSDs, it strikes an ideal balance between speed, lifespan, and cost-effectiveness. More than sufficient for daily use, it typically lasts 3 to 5 years or longer.
4. QLC (Quad-Level Cell): Stores four bits per cell. It provides large capacities at low per-unit prices but suffers from slower speeds and shorter lifespans. It is only suitable for mass storage and not recommended for installing operating systems or applications.

For first-time buyers, prioritize TLC-based SSDs and steer clear of low-quality QLC white chips or black chips (salvaged or defective recycled chips).

Many users buy M.2 SSDs but experience poor performance simply because they ignore protocol compatibility:

1. SATA Protocol SSDs: Use the SATA 3.0 interface with a maximum speed of 550MB/s. Compatible with traditional hard drive interfaces, making them the best choice for upgrading older computers.
2. NVMe Protocol SSDs: Use the M.2 interface and run on PCIe lanes. They are categorized by generations:

• PCIe 3.0: Speeds range from 2000–3500MB/s
• PCIe 4.0: Speeds range from 5000–7000MB/s
• PCIe 5.0: Speeds exceed 10000MB/s
• For most PC builds, PCIe 3.0 or 4.0 SSDs are more than enough, with little noticeable difference in daily usage.

The SSD controller manages data read/write operations and wear leveling. High-quality controllers from brands like Silicon Motion, Phison, and Marvell enhance speed and extend lifespan, while low-quality controllers often lead to slowdowns, blue screens, and drive disconnections. When purchasing, stick to reputable brands such as Samsung, Western Digital, Kingston, Zhitai, and Kioxia for better reliability.

SSD lifespan is measured by TBW (Terabytes Written). For example, a 1TB SSD with a TBW rating of 600 can withstand a total of 600 terabytes of data written over its lifetime. The average daily user writes less than 50TB of data per year, so lifespan is rarely a concern in regular use.