Question Asus B450-I will not recognize rear M.2 SSD

[lsma]

My ASUS B450-I has two M.2 slots, one on the front (which can do SATA or NVMe) and one on the back (only NVMe). I originally had an NVMe drive (Linux boot) in the front slot. I got a new SATA M.2 drive, and so I moved the NVMe drive to the rear slot and replaced it with the SATA drive up front (since only the front slot supports SATA). The problem is that the NVMe now plugged into the rear M.2 slot will not show up (not in Linux lshw, Windows disk manager, or the BIOS). I am at my wit's end trying to discover why the mobo will not recognize it. Extensive googling has not turned up anyone who has experienced this. I have:

• Updated the BIOS to the most recent version (4801)
• Fiddled around with enabling/disabling things in the BIOS (e.g., CSM, PCIEx16 Bandwidth, etc.)
• Re-re-installed the NVMe drive (99% sure the installation is correct---no visible copper pads)
• Removed everything except the NVMe drive (still a no show)
• Re-installed the NVMe drive in the front M.2 slot (it still works fine---the drive has not failed or anything like that)

The only thing I have not done is to test it with a different NVMe drive, but I suspect it still would not be recognized. It seems like the motherboard is just refusing to notice it.

The rear M.2 connector shares bandwidth with the main PCIex16 connector, so that when you plug in an NVMe SSD in the back, your graphics card goes down to x8 mode. To all appearances (both in the BIOS and in AMD's software), my Radeon GC is running in x8 mode, so this should not be the problem, unless something fishy is happening with how the PCIe lanes are being allocated. Really hoping that I won't have to resort to ASUS customer service!

• Asus ROG STRIX B450-I (BIOS version 4801, latest) manual
• AMD Ryzen 5 2600 (no OC)
• 2x8GB Crucial Ballistix DDR4-3200
• Sapphire Radeon RX 580 8 GB NITRO+ (according to AMD software and BIOS running in x8 mode)
• Samsung 960 EVO M.2 NVMe SSD (500GB) <--- Linux boot drive in M.2_2 back side (does not show up)
• Samsung 860 EVO M.2 SATA SSD (500GB) <--- Unformatted drive in M.2_1 front side (shows up)
• Samsung 860 EVO SATA SSD (500GB) boot drive <--- Windows boot drive plugged into a normal SATA connector (shows up)
• Corsair SF 600 (600W 80+ gold)

 

[Deleted member 362816]

Have you been able to test this on a different system yet? I looked at the manual, as long as you are in ACHI for SATA mode it should function and show.

 

[lsma]

I did not try the SSD in a different system, but I did install my friend's SSD in the same place and it also failed to show up. I have pretty much come to terms with the fact that the port is dead. It'll just have to wait till my next MOBO upgrade, since there is no way in hell I am going to go through ASUS RMA.