ROG Crosshair x870e Apex can see one m2 drive but not the other

[Bronzewing]

I've upgraded my work/gaming PC to the x870e Apex motherboard and for some reason it can only see one of my two m.2 drives.

One of my M.2 drives (Samsung SSD 970 EVO Plus 1TB) works perfectly well in the M.2_1 slot, but my other one (Samsung SSD 860 EVO M.2 2TB) can't even be seen by the BIOS in any of the other slots (I've tried it in M.2_2, M.2_3, and both DIMM.2 slots).

I've tested the 860 using a USB enclosure and the drive itself is working perfectly (CrystalDiskInfo confirms that it's healthy and running properly), so the motherboard must be the issue. Do I need to tell it to accept legacy (SATA) m.2 drives, or could it be a faulty motherboard?

BIOS Date (the latest as of writing): 11/12/2025
BIOS version: 1804

I've updated the chipset drivers and everything else that Armoury Crate offered.

My hardware:
AMD Ryzen 9 9900X
ASUS ROG CROSSHAIR X870E APEX
ASUS ROG STRIX RTX 4090 GAMING OC
32GB DDR5 (Corsair CMK32GX5M2B6400C36 - 2 sticks)

I currently have three other drives connected to the regular SATA ports on the board - two are 3.5" HDDs and one is a 2.5" SSD.

[Bronzewing]

UPDATE: I realised the only thing I hadn't tried was plugging the 860 EVO into the motherboard's m.2_1 socket (in place of my boot drive). Tried it, and the BIOS couldn't see any device connected to that socket. Put the boot drive back in and put the 860 back in a USB enclosure and confirmed that the 860 is still running fine, except the motherboard can't see it in any m.2 slot even though it can see the 970.

[Bronzewing · Accepted solution]

I got an official answer from ASUS Support.

TL;DR: The Crosshair x870E Apex doesn't support SATA-based M.2 drives (which would have been nice to know beforehand, since I was under the impression that PCIE M.2 slots are normally backwards-compatible with SATA M.2 drives).

Here's the full response:

We understand the concern regarding your Samsung SSD 860 EVO M.2 drive not being detected on the ROG CROSSHAIR X870E APEX motherboard.

Based on the information provided, please note that the Samsung 860 EVO M.2 is a SATA-based M.2 SSD. The motherboard’s M.2 slots are designed primarily for PCIe NVMe SSDs. SATA-based M.2 drives are not supported on these slots, which is why the BIOS does not register the device.

https://rog.asus.com/motherboards/rog-crosshair/rog-crosshair-x870e-apex/spec/

For direct motherboard installation, we recommend using NVMe-based M.2 SSDs for full compatibility with the X870E APEX. Alternatively, consider installing a SATA 2.5" SSD via the standard SATA ports.

You may still use the Samsung SSD 860 EVO with an adapter or enclosure, as you have already confirmed it works in a USB enclosure.

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[Silent_Scone]

Hi @Bronzewing 

In the user manual, the storage specification lists each onboard M.2 slot as supporting only PCIe x4 mode. No SATA mode is listed, and the DIMM.2 card is described as supporting PCIe storage devices only.

Perhaps this isn't as direct as it could be; however, there is no explicit mention of SATA NVMe support anywhere.