Question Samsung 870 EVO 1TB SSD - - - Low read/write speeds ?

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Feb 22, 2023
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I'm "happy" owner of Samsung 870 EVO 1TB SSD. The read speed is a half of rated (only 283 MB/s). What is even more disappointing - the read speed is almost a half of my old SanDisk SD9SN8W-128G SSD (507 MB/s). What could be a reason?

My notebook is HP 250 G6. SanDisk SSD is connected to M2 SATA port on the motherboard. Samsung 870EVO is connected to a regular SATA port installed instead of the second M2 SATA port (connected to the motherboard via a flat cable). By the way, the write speeds for both mentioned SSDs are approx. 250 MB/s. A half of rated write speed for Samsung 870EVO :(

UPD1: On installing the latest BIOS for my laptop (version F.70 of 2022) the situation became even more dramatic - no changes in speeds for Samsung, but higher sequential read speed for SanDisk (540 MB/s). I used the latest CrystalDiskMark for benchmarking.

UPD2: CrystalDiskInfo reports that Samsung SSD is in SATA/300 mode while maximum possible mode is SATA/600. Whereas SanDisk SSD is in SATA/600 (maximum is SATA/600). This info explains the results of benchmark, BUT why my new Samsung 870 EVO is in SATA/300 mode???? I also have an HDD installed in my system (instead of optical disk drive). It's funny but it operates in SATA/600 mode as well! Samsung's Firmware is of the latest version (SVT02B6Q). Here is the picture of the flat cable with SATA socket I used to connect Samsung SSD to the motherboard: link to the picture .

UPD3: I decided to do some experiments trying to 1) understand the reason, 2) find solution for my situation.
  1. I left the Samsung as the only hard drive in the laptop, connected via flat cable to the MB (SanDisk and Seagate HDD are removed). No changes in speed. Samsung is still in the SATA/300 mode.
  2. I put the Samsung to the adapter instead of the Seagate HDD (the adapter is a replacement of the DVD drive). The effect is WOW! The Samsung is in the SATA/600 mode (as HDD was before). Read/write speeds are 562MB/s / 527 MB/s. Awesome!
  3. I added SanDisk connected to the M2 SATA on the MB. Both are in SATA/600 mode. Speeds are top!
  4. All I had to do is to connect Seagate HDD to the socket (with the flat cable) where I tried to connect the Samsung initially. Who cares? - Its speeds are 60MB/s, so SATA/300 should be enough. But what the hell!!! CrystalDiskInfo shows that HDD is in SATA/600 mode... :)

I still don't understand what's going on, but I've got a configuration, which gives maximum speeds from my drives!
 
Last edited:
Feb 22, 2023
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Sometimes a SATA device or host will negotiate a lower link rate if there are too many communications errors at the higher rate.

Try GSmartControl. There may be something in the logs that will help us to see what is happening.

Thanks! Yes, it could be a reason, but SMART info for both SSDs shows that all error-related parameters are 0. Please, check UPD3 in my original post.
 

USAFRet

Titan
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You do know that there are 3gbps and 6gbps Sata wires don’t you? You likely have a slower wire and need an upgrade.
Actually, no.
 
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