SSDs are expensive but not necessarily fast: the interface protocol and main control are the key
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SSDs are expensive but not necessarily fast: the interface protocol and main control are the key
Solid-state drives (SSDs) are the most obvious upgrade direction to speed up computers, but the product parameters on the market are confusing—some 1TB cost less than 300 yuan, and some cost 800 yuan for the same capacity. What’s the difference? Most consumers can't tell the difference, and the pitfalls are mainly concentrated in the three areas of interface, protocol and cache.
Interface type: determines the physical installation method
There are three common interface forms of SSD:
| Interface | Typical specifications | Connection method |
|---|---|---|
| SATA | 2.5-inch, M.2 2280 (using SATA protocol) | Motherboard SATA interface or M.2 SATA |
| M.2 NVMe | M.2 slot, PCIe channel | Direct plug-in motherboard M.2 slot |
| PCIe direct plug | graphics expansion card | PCIe x4 slot, server/fever oriented |
The first two are commonly used at the consumer level:
- SATA SSD (M.2 or 2.5 inches): The upper limit of reading speed is about 550MB/s, and the writing speed is about 520MB/s. It is cheap and suitable for upgrading old machines.
- NVMe M.2 SSD: read speed 3000–7000+ MB/s, 5–10 times faster than SATA, suitable for new platforms
Determine whether M.2 is SATA or NVMe:
- Look at the location of the golden finger notch: SATA only has one notch (B+M key); NVMe usually only has one notch for M key.
- Look at the price: SATA with the same capacity is cheaper
- Look at the motherboard specifications: The M.2 slot states whether it supports NVMe, SATA or is compatible.
Protocol version: PCIe 3.0 vs 4.0 vs 5.0
The protocol determines the total bandwidth of the data transmission channel:
| Protocol | Theoretical maximum bandwidth (x4 channels) | Sequential reading speed upper limit |
|---|---|---|
| PCIe 3.0 NVMe | ~4 GB/s | ~3500 MB/s |
| PCIe 4.0 NVMe | ~8 GB/s | ~7000 MB/s |
| PCIe 5.0 NVMe | ~16 GB/s | ~14000+ MB/s |
Actual usage perception:
| Scenario | SATA | PCIe 3.0 NVMe | PCIe 4.0 NVMe |
|---|---|---|---|
| System startup | About 12–15 seconds | About 10–12 seconds | About 9–11 seconds |
| Large game loading | Significantly slow | Fast | Slightly faster |
| Large file transfer (100GB+) | Slow | Fast | Significantly fast |
| Ordinary daily use | No difference can be felt | No difference can be felt | No difference can be felt |
Conclusion: PCIe 3.0 is sufficient for daily office use, gamers recommend PCIe 4.0, and creative workers (video editing/large file transfer) consider PCIe 4.0 or 5.0.
With cache vs without cache: affects sustained writing speed
DRAM cache (independent cache):
- An independent DRAM chip is used as a buffer, and the main control is fast and stable when reading and writing frequent small blocks of data.
- Not easy to slow down when writing a large amount of data
- higher price
No cache (HMB or pure no cache):
- HMB (Host Memory Buffer): Borrowing system memory for buffering, which is better than pure no cache, but continuous writing will still slow down
- Pure no cache: cheap, speed will drop from 3000MB/s to about 800MB/s after continuous writing of 10–30GB
- Suitable for scenarios that do not require high speed (light office, archive disk)
Which scenario requires caching:
- System disk: DRAM cache is strongly recommended
- Video editing work disk: cached
- Pure data backup/archive disk: no cache + large capacity and high cost performance
Main control: determines stability and lifespan
The main control is the "CPU" of the SSD and is responsible for scheduling read and write, wear leveling, error correction and other tasks.
Key Parameters:
- TBW (total write volume): represents the total amount of data that can be written to the hard drive during the warranty period. 1TB capacity usually has a TBW of 300–600TB.
- MTBF (Mean Time Between Failures): Usually marked as 1.5 million hours, this is a theoretical value, for reference only
- Disk drop problem: Some low-end controllers will feign death (disk disappears) when exposed to high temperatures or when writing a large amount of data, seriously affecting use.
TBW Reference:
| Usage intensity | Daily writes | Recommended TBW (1TB) |
|---|---|---|
| Light (office browsing) | About 20GB | 300TB is adequate (40 years of use) |
| Moderate (Gaming/Creative) | About 50–100GB | Above 500TB |
| Heavy (Server/Lots of Clips) | 200GB+ | 800TB+ |
Heat dissipation: hidden dangers of M.2 SSD
The temperature of high-speed NVMe SSD can reach 80–90°C when fully loaded, and the speed will drop significantly after triggering thermal protection.
Solution:
- The motherboard has an M.2 heat dissipation sticker, do not remove it (many people think it is a protective film and throw it away)
- PCIe 4.0/5.0 disks are recommended to be equipped with an aluminum heat dissipation vest or an adapter card with active heat dissipation.
- The air duct inside the chassis is good and the temperature is naturally low
Capacity planning
| Purpose | Recommended capacity |
|---|---|
| Pure system disk + several commonly used software | 256GB (not recommended, fills up quickly) |
| System + daily software + several games | 1TB starting (recommended) |
| Main creative work computer (video/design) | 2TB or more |
| Dedicated game storage disk | 2–4TB |
Shopping list
| Core Parameters | Recommendations |
|---|---|
| Interface protocol | NVMe PCIe 4.0 (mainstream recommendation) |
| DRAM cache | System disk must have |
| TBW | 1TB capacity recommended ≥ 300TB |
| Warranty | 3–5 years (with TBW coverage) |
| Cooling | M.2 PCIe 4.0 with vest |
*The technical parameters in this article are derived from storage industry standards and mainstream evaluation methods, and do not represent recommendations for specific brands or models. *