Question M.2 SSD running at PCIe x1 on a x4 m.2 slot

Jul 1, 2022
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My motherboard is a MSI B550-A Pro, with two m.2 slots:
m.2_1, gen 4
m.2_2, gen 3 (when using this the second x16 PCIe slot is unavailable)

I always used my Samsung 970 EVO Plus 1TB as boot drive on m.2_1 and it always run at almost its max speed, but recently the speed dropped at ~880 MBps. Both Samsung Magician and CrystalDiskInfo say the SSD is running at PCIe 3.0x1 instead of 3.0x4. I tried to reboot my pc many times, but nothing changed. I moved my SSD to m.2_2 slot and it worked fine at x4. Then i tried to use a 500GB SSD of the same model on m.2_1 and it ran at x1. So i assume the issue is the slot and not the SSD, unless it's a issue about 970 EVO plus SSDs, but i don't think so (they're both updated at last version and Magician say they're working fine).
The BIOS let you set the gen of PCIe, but not the number of lanes. So i don't know wich settings i should chek.
Currently i only use 1 SSD in the first m.2 slot and i don't use any of the PCIe slots. I use a sata port for a 2TB HDD, but i added it before this issue.


Could it be that the m.2 slot is damaged?
 
Last edited:

Lutfij

Titan
Moderator
Welcome to the forums, newcomer!

What BIOS version are you currently on for your motherboard? As for your SSD, did you install the NVMe driver meant for your SSD? What OS are you working with?
 
Jul 1, 2022
2
0
10
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Welcome to the forums, newcomer!

What BIOS version are you currently on for your motherboard? As for your SSD, did you install the NVMe driver meant for your SSD? What OS are you working with?
Thanks for the welcome.

I'm running Windows 11 Home 21H2 and i hace already checked for driver updates.
My current BIOS is 7C56vA9, relased on 18 march. MSI relased a new version on 26 may. Should i update?
 

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