Question Samsung 970 EVO PLUS NVMe M.2 Slow Read Speed

Oct 22, 2021
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Hello, I know that the problem is common, but still didnt find solution.

The speed for my SSD drive is at half the rated speed (~1700MB/s). I am unsure why.

System: ASUS Q325UA (aka UX370UA) notebok + Samsung 970 EVO PLUS
Samsung drivers installed

What I'm doing wrong?

 
Oct 22, 2021
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run hwinfo during that test and look up for your drive temperature during test, it could be overheating, those little things heat up quite a bit without heatsink under load
Drive Temperature : increased from 31 to 44
Drive Temperature2: increased from 36 to 48
 
Oct 22, 2021
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Only using two lanes. This is not uncommon in some laptops, they throttle to two lanes even if it says x4. Some sources refer to this as "GT2" as it typically happens on specific chipsets with integrated GPUs.
Thank you! Seems you are right. Is there any way to check it for sure?
 

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Thank you! Seems you are right. Is there any way to check it for sure?
8 GT/s is per lane, and while it supports 4 lanes these chipsets limit it to 2. 8 GT/s with 128b/130b encoding times two is approximately 1.97 GB/s. There's also ~10% of overhead which gives a maximum of around 1772 MB/s. This matches your result precisely, which is how I knew.

Unfortunately this is a limitation on some models depending on how they implement the chipset. You shouldn't be overly concerned about it, since in most cases you won't be reading or writing to that drive faster than that - since you can't have other sources that could match it on that system. It is possible to write to itself, of course, but these drives have limited SLC caches such that the native TLC speed is actually slower than x2 PCIe 3.0. There are limited cases in the future where the missing sequential reads could be useful - Windows 11, DirectStorage, and games several years from now - but I suspect you wouldn't be playing these games on that machine.
 

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