Brand new Samsung 990 Pro 4TB NVME M.2 very slow write speeds at ~800MB/s

[userzsyhcRg7PW]

Hello,

I just installed a Samsung 990 Pro 4TB NVME M.2 SSD from into my Gigabyte b550i pro AX mini-itx motherboard. The new 990 Pro 4TB is in the designated PCIE 4 slot at the top of the motherboard under the heatsink. Samsung Magician indicates it is on the latest firmware and that there are no compatibility issues. I used Macrium Reflect to clone the 1TB to the new 4TB and reinstalled the boot partition on the 4TB.

I ran a benchmark and have no idea why I am getting such low sequential and random write speeds. See below for the screenshots, sequential and random writes are around ~800 MB/s:

https://imgur.com/a/mSeKRSu

I checked temperatures and during benchmarking everything is sub 60C. I checked the MiniTool Shadow utility to perform 4k alignment and it indicated that it was already 4k aligned and was not needed.

I double checked the drivers which were the latest pre-installed. I ran multiple benchmarks in Crystal Mark Disk with the same result. I verified in the BIOS that the PCIE lanes were set to Auto to auto detect (no idea how I would get over 6k reads on PCIE 3).

At this point I assume the drive is defective and I'm ready to RMA and revert. Any ideas what might be wrong with the drive? Did I do something wrong or am I missing something?

Even with sustained writes for even 1 second and smaller write size (512MB, 256, etc) the result is still the same. 800 MB/s seems exceptionally low.

Even in other benchmarks across the internet the typical lowest the sustained sequential write drops to is around 1.5GB/s: https://www.reddit.com/r/hardware/comments/1146b0s/ssd_sequential_write_slowdowns/

I've tried formatting it twice and I still get the same result. I'm on Windows 10 with the latest updates as well. I'm assuming the drive is defective at this point because I don't know what else could cause this.

Thank yo for your time!

[Srb79]

I believe 990 requires PCI 5 to get full transfer speed.

[ddaniel51]

The 990 is a Gen 4 SSD and I have 6 of them in my Xeon workstation.  They will run 6000 MB R/W on a proper Gen 4 MB/CPU combination but, can be throttled by low cost/performance MB/CPU systems.

Use Samsung Magician.

The 4 yr old 550i started out life as a low cost entry level gen 3 MB with provisions for gen 4 abilities via bios  updates depending on which M.2 slot is used.  Actual performance levels are dependent on bios version, CPU and Memory used.  Read the User Manual.

Let us know how it works after you replace the 990.