TechSpot benchmarks highlight importance of selecting the correct M.2 slot for best performance

An Asus motherboard showing the rated throughput of the M.2 slots. (Source: Asus)
An Asus motherboard showing the rated throughput of the M.2 slots. (Source: Asus)
Enthusiasts who want the fastest possible storage speeds already know to buy motherboards that use flagship chipsets (e.g. Intel's Z370 and AMD's X470). However, a series of benchmarks from TechSpot confirm that dual slot X470 boards can restrict performance if one of the slots is connected to the chipset with PCIe 2.0.
Craig Ward,

NVMe SSDs that utilize PCIe lanes via M.2 or via a PCIe slot offer a large increase in data throughput over SATA based drives. It is commonly said that a PCIe x4 slot is all that is needed to get the full benefit from these drives, but TechSpot has recently tested three setups that show how the motherboard chipset can degrade performance.

TechSpot took an Adata XPG SX8200 (the 960 GB version), which uses four NAND 3D TLC chips and two DDR3 chips as a buffer combined with a high-speed controller and support for the PCIe 3.0 specification. They tested using Intel’s Z370 and AMD’s X470 chipsets. On this Z370 motherboard, the M.2 slots connect via the chipset but use an interface that is fast enough not to restrict PCIe 3.0 x4. On the X470 motherboard, there was one M.2 slot that was direct to CPU but the other was piped via the chipset and the slot to chipset connection is restricted to PCIe 2.0 speeds.

The first and most obvious restriction is in maximum speeds during sequential read and write tests. Tests performed using AS SSD Benchmark 2.0 (sequential read/write, ISO copy) and ATTO Disk Benchmark (sequential read) show a maximum attainable speed of around 1300 – 1400 MB/s depending on whether the data is compressible or not. This is compared to 2700 – 3000 MB/s read or 1650 MB/s write speeds achievable by the Adata drive using other M.2 slots.

It was interesting to see that this difference also showed in small file read performance (16 to 64 KB), where even though the drive wasn’t hitting the same speeds as it would during sequential, the one connected via PCIe 2.0 still lagged behind. Although we did think that these differences wouldn’t be noticed by most people during daily use unless your workflow involved regularly transferring a lot of data on and off the drive. 

This shows that you should always check the rated speeds of your motherboard’s M.2 slots before installing your shiny new M.2 drive to ensure you are getting the best performance you can. For more details, we recommend reading through Techspot’s comparison and checking out the additional graphs.



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> Notebook / Laptop Reviews and News > News > News Archive > Newsarchive 2018 06 > TechSpot benchmarks highlight importance of selecting the correct M.2 slot for best performance
Craig Ward, 2018-06-25 (Update: 2018-06-25)
Craig Ward
Craig Ward - News Editor
I grew up in a family surrounded by technology, starting with my father loading up games for me on a Commodore 64, and later on a 486. In the late 90's and early 00's I started learning how to tinker with Windows, while also playing around with Linux distributions, both of which gave me an interest for learning how to make software do what you want it to do, and modifying settings that aren't normally user accessible. After this I started building my own computers, and tearing laptops apart, which gave me an insight into hardware and how it works in a complete system. Now keeping up with the latest in hardware and software news is a passion of mine.