1

I am in the process of upgrading multiple laptops: a Lenovo L14 AMD, an E15 AMD and a recently ordered Lenovo L14 G2 AMD (5750U) with a 1TB SSD. I was wondering if I should be using the Western Digital SN750 (PCIe 3.0) or the SN850 (PCIe 4.0), as the notebooks of course only support PCIe 3.0.

It should be generally possible to install the newer drive because of its backwards compatibility, but there are no tests or reviews out there which would explain benchmarks, or anything else in this regards.

My concrete question is: can anyone please explain if if would make sense to install a PCIe 4.0 SSD in a PCIe 3.0 slot, and what the data rates would approximately be. Bonus points for explaining the differences on the Western Digital drives which i am eyeballing.

Improve this question
6
  • 1
    My concern would be on potential device model "whitelisting" in the UEFI. I know that the laptop vendor(s) do it for WLAN modules. Not sure about NVMe SSDs.
    – Tom Yan
    Commented Jun 4, 2021 at 19:34
  • 1
    The newer and more expensive should work (except in the aforementioned case of "whitelisting" which is very rare) but there's no point, comparatively, because it'll be limited to the v3.0 speeds.
    – ChanganAuto
    Commented Jun 4, 2021 at 19:40
  • What do you mean? I did replace SSDs in laptops before, and it was not a problem. But interesting concern :)
    – OpenGears
    Commented Jun 4, 2021 at 19:40
  • 1
    If you install a PCIe 4.0 device, into a device that only supports PCIe 3.0, it will of course only run at PCIe 3.0 speeds. The performance speeds of the device itself, would depend on the type of flash memory the device uses, but would be limited by the PCIe 3.0 bandwidth. Why exactly do you have a SN850 if you don't have a device that support it's true performance? Q&A format is a horrible venue to compare two products, especially when hardware recommendations, are explicitly NOT allow here on Super User.
    – Ramhound
    Commented Jun 4, 2021 at 19:40
  • Thanks for the comment Ramhound. I am asking this question for exactly this reason - because the PCIe bandwidth would be the limit, i am wondering of the actual performance of the SN850 and if it would perform better than the SN750 in this case.
    – OpenGears
    Commented Jun 4, 2021 at 20:03

2 Answers 2

Reset to default
0

The SN750 uses PCIE x4, while the SN850 uses PCIE x8.

The Lenovo L14 AMD only has PCIe 3.0 x4.

So the answer: Your computer is incapable of using the SN850 for better performance.

In general, installing a PCIe 4.0 SSD in a PCIe 3.0 slot might get a minuscule and unnoticeable performance boost, so is not worth the effort.

You may find more information in the article What Is PCIe 4.0 And Is It Worth It For Gaming?

Improve this answer
7
  • Thank you very much for the quick and precise answer.
    – OpenGears
    Commented Jun 4, 2021 at 20:41
  • M.2 supports up to 4 lanes. PCIe 4.0 provides more bandwidth per lane doesn't make it x8.
    – Tom Yan
    Commented Jun 5, 2021 at 9:09
  • @Nanofunk Besides, if the NAND on SN850 is faster, it could still provide non-trivial performance gain in random or even sequential operations. (Remember that, the "spec" are often "peak maximum", i.e. it may/will not be able to make use of all the bandwidth all the time.)
    – Tom Yan
    Commented Jun 5, 2021 at 9:14
  • @TomYan: Unclear: The limiting speed is the computer's PCIe 3.0 x4. You can't go any faster than that, even if the disk can do PCIe 4.0 speeds and has fast NAND.
    – harrymc
    Commented Jun 5, 2021 at 9:25
  • @harrymc: If you have read any relatively-detailed review on any NVMe SSDs, you will know they will start to slow down after their faster SLC "cache" is full. So even the SN850 will probably not be able to maintain at the speed that will fill the bottleneck of PCIe 3.0x4 for lengthy sequential write (let alone random read/write). If the slower NAND chips in it are faster than those in an SN750, you could still benefit from that even if you put it onto a PCIe 3.0 slot.
    – Tom Yan
    Commented Jun 5, 2021 at 9:54
0

Here's the video testing samsung 970 evo plus vs 980 pro (which is similar to sn750 vs sn850)

https://www.youtube.com/watch?v=O1WlzO97VfA

Improve this answer
1
  • 1
    Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.
    – Community Bot
    Commented Oct 25, 2021 at 7:35

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .