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Solid-state hard drives have developed rapidly along with development of computers in recent years. There is currently a slight trend towards replacing mechanical hard drives and it is only a matter of time before they replace mechanical hard drives.

At same time, SSD manufacturers will continue to ramp up storage capacity. Under dual influence of a significant increase in initial production capacity and launch of 96-layer 3D flash memory, price of flash memory has declined. memory products will have a larger rolloff. Today, some SSDs have already reached level where they cost less than 1 yuan per 1 GB.

With strong technology support, it's hard to stop decline in NAND flash prices. This is definitely great news for us. However, concept of SSDs is indeed cumbersome, and the publicity accumulated by overwhelming "technical terms" may make many small partners "know it but not know why."

When buying SSDs, many friends only see sellers advertising NVMe and PCIE SSDs, but don't understand what that means. Today I will briefly explain to you what these "professional terms" mean.

Let's first understand between M2 and SATA. We often say that M2 is actually M.2, which refers to size or slot of SSD, which is on right in picture below with a smaller size and is directly connected to motherboard, and SATA it also usually refers to left side of picture below. A large piece of this size is larger.

At same time, there are two types of M.2 connectors: a Socket 2 connector with two gaps in gold pin, and a Socket 3 connector with only one gap in gold pin. These two types can use different channels.

Socket 2 solid state can use either SATA3 or PCI-E 3.0x2 (i.e. two PCI-E) links, and Socket 3 solid state can use PCI-E 3.0x4 links. The SATA slot usually only uses SATA3 link. Everyone should remember that bandwidth of each PCI-E 3.0 is 8 Gb / s, while bandwidth of SATA 3.0 is only 6 Gb / s.

The next thing to distinguish is SATA and PCIE, which refers to a serial interface or channel over which data is transferred. Note that SATA above refers more to slot, while SATA here refers to channel through which data passes. Current new devices usually use SATA3 interface (but SATA3 is backwards compatible with SATA2 and SATA1), so it's usually used. It's called SATA3.

To put it simply, PCI-E and SATA3 are "roads" for information and data. PCI-E is a particularly wide road and data can be transferred very quickly, while SATA3 is like a small road and data moves relatively slowly. But there is just enough space inside CPU, so there are only a few PCI-E channels.

However, NVMe is often used as a selling point by sellers. If SATA and PCIE are "roads", then NVMe and AHCI are actually "rules of road" on that road. If there is no traffic restriction, then this data will also be overflowed (we are no different).

AHIC is "traffic rule" for SATA, but developers found that specification's rule that data can only be transferred one at a time is too wasteful to use on a spacious PCIE link. Therefore, NVME specification was developed for PCIE channel, allowing a large amount of data to pass simultaneously. Therefore, NVMe protocol is more efficient than AHCI protocol used by SATA.

Of course, above is just an explanation of some of professional terms, and there are many things to consider when buying an SSD. While prices of some SSDs have dropped on market, you still need to do your homework before buying one so you don't fall into pit due to "professional knowledge" of merchants.