Strix 870-i drops Gen 5 SSD from BIOS - intermittent.... No end in sight?

[Tbone36]

Built a new Strix 870-I with 2 SSD's (Gen 5) Corsair MP700 Pro and a (Gen 4) Samsung 990 Pro. Both 4 TB.

I first built this with the MP700 as C Drive and 990 as D Drive but did not have them in the right slots. MP700 was in M.2_2 and the 990 was in M.2_1. This was by accident because I wanted the Gen 5 in the M2_1 slot to take advantage of the increased bandwidth....but I didn't realize it until a couple of months later. Nevertheless, I really had no issues and everything was working fine.

So just yesterday I decided to "swap" the drives so that the MP Gen5 would sit in the m2_1 slot and the 990 in the M2_2.

THAT's when the headaches started. The computer randomly dropped the MP700 from the BIOS, but random probably means "more often than not". I upgraded/downgraded BIOS a few times, I did every suggested solution on any site I could read up on... NOTHING worked. BIOS changes, "fast-boot" off, forced PCIe 8x8 etc. etc...... Nothing worked. I removed, re-seated the MP700.... nothing. Still as flaky as ever.... wasted hours trying to figure this out! I need a system that is ultra-reliable becasue of the work I do, and I can't afford to turn it on wondering whether or not it will boot or just go into BIOS!!  Very frustrating! The "Boot Manager" in the BIOS doesn't even load up. There is no options. I even removed the 990 completely and JUST had the MP700 in the M2_1 slot....and STILL it randomly dropped the drive in the BIOS....

Finally,I  had enough and switched the drives back to their originally installed position. THAT cleared it up. the computer is running FINE now and has been cycling many times without dropping anything in the BIOS.

So, now I'm quite sure it is either a generic "Gen5" issue in the M2_1 slot, or perhaps certain Gen5 - like CrucialT700 or Corsair MP700 series.. PLEASE ASUS, I've had enough and wonder why I spent the Xtra money on a Gen 5 - and I can't even USE it!!

We NEED a solution whether it be from ASUS, or confirmation that it is a Corsair/Crucial/Gen5 issue!!

[Jiaszzz_ROG]

Hello @Tbone36,

Thank you for reaching out to us.
May I ask which CPU model you are currently using? If you are using a Ryzen 8000 series CPU, please note that the M.2_1 slot will only support PCIe 4.0 x4.

If you are using a Ryzen 9000 or 7000 series CPU, could you kindly provide the following details to assist us in further investigating the issue?
- The BIOS versions you have tested, the specific manual adjustments made, and whether you have cleared CMOS in these versions to confirm if the issue persists under default BIOS settings.
- The OS version and build, as well as the driver and firmware versions for the Corsair MP700 Pro.
- The brand, model, and installation slots or ports for the CPU, GPU, RAM (including part numbers), HDD, and PSU. 
Additionally, please specify whether any extensions or adapters are used to connect any devices, such as the GPU or SSD.
- The specific circumstances and frequency of the issue.
And to further analyze the situation, please provide video recordings of system stability or instability under the latest BIOS version after clearing CMOS and with no manual adjustments in the following three scenarios:
1) Corsair MP700 Pro installed in M.2_1, with M.2_2 left empty
2) Corsair MP700 Pro installed in M.2_1, Samsung 990 Pro installed in M.2_2
3) Samsung 990 Pro installed in M.2_1, Corsair MP700 Pro installed in M.2_2

Your cooperation in sharing these details would be greatly appreciated. Thank you.