How to Fix the “Axc/Unknown” NVMe Detection Bug in CrystalDiskInfo

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How to Fix the “Axc/Unknown” NVMe Detection Bug in CrystalDiskInfo

You plug in a brand-new, blistering-fast M.2 NVMe drive, boot up your PC, and immediately fire up CrystalDiskInfo to check your new toy’s temperatures and health stats.

But instead of seeing your exact drive model, you are greeted by a frustrating sight: the drive model is labeled as “Axc” or simply listed as an “Unknown NVMe Device.” Even worse, your S.M.A.R.T. attributes might be completely greyed out, or the health percentage box displays nothing but a blank dash.

Don’t worry—your new SSD isn’t broken, and it isn’t a fake. This is a common communication breakdown between the Windows storage drivers, your motherboard’s controller, and CrystalDiskInfo itself.

Here is exactly why this detection bug happens and how to fix it in under five minutes.

Why Is CrystalDiskInfo Showing “Axc” or “Unknown”?

CrystalDiskInfo is an incredible tool, but it doesn’t talk to your SSD directly. It sends a command through Windows to your motherboard’s storage controller, asking for the drive’s firmware signature.

When you get an “Axc” or “Unknown” error, it means the data stream got scrambled or blocked along the way. This almost always boils down to three main culprits:

  1. The Intel RST / RAID Driver Trap: If your motherboard’s BIOS is configured to use Intel Rapid Storage Technology (RST) or RAID mode instead of AHCI/NVMe passthrough, Windows hides the raw S.M.A.R.T. data behind a software wall.

  2. Third-Party USB Enclosures: If you are using an external M.2 to USB enclosure (like an Orico or Asus ROG Strix Arion), the bridge chip inside the enclosure might not be passing the NVMe telemetry data correctly.

  3. Outdated Controller Maps: Your version of CrystalDiskInfo might simply be too old to recognize the firmware string of a newly released flash controller.

Step-by-Step Fixes to Restore Your NVMe Detection

Work your way down this checklist to force CrystalDiskInfo to properly communicate with your drive.

Fix 1: Change the Advanced Disk Search Settings

Before tweaking your system drivers, try changing how CrystalDiskInfo scans your hardware. The software has built-in safe modes that can sometimes bypass stubborn system controllers.

  1. Open CrystalDiskInfo.

  2. Click on the Function tab in the top menu bar.

  3. Hover over Advanced Feature and look for Disk Search.

  4. If your drive is an external USB enclosure, make sure [USB] is checked. If it’s an internal drive giving you errors, toggle the advanced detection settings or click Rescan to force a fresh hardware query.

Fix 2: The Motherboard BIOS Fix (Switch RAID to AHCI/NVMe)

This is the single most common reason internal NVMe drives show up as “Unknown.” Many pre-built PCs (especially from Dell, HP, or Lenovo) ship with the storage controller set to RAID/Intel RST mode in the BIOS by default, which blocks standard telemetry.

  • The Fix: You need to enter your motherboard’s BIOS/UEFI screen during startup (usually by tapping F2 or Delete as the PC turns on). Locate your storage configuration settings and change the SATA/Storage mode from RAID or Intel RST to AHCI or NVMe Passthrough.

⚠️ CRITICAL NOTE: Changing this setting blindly can cause Windows to give you an “Inaccessible Boot Device” blue screen on startup. To prevent this, boot Windows into Safe Mode first, change the setting in your BIOS, and then boot back into normal Windows so the operating system can automatically swap to the correct standard NVMe driver.

Fix 3: Update to Standard Windows NVMe Drivers

Sometimes proprietary storage drivers from your motherboard manufacturer conflict with standard tracking software. Swapping back to the native Microsoft driver often instantly fixes the bug.

  1. Right-click the Windows Start Button and select Device Manager.

  2. Expand the Storage controllers section.

  3. Look for anything labeled “Intel Rapid Storage” or a proprietary controller. Right-click it and choose Update driver.

  4. Select Browse my computer for drivers > Let me pick from a list of available drivers on my computer.

  5. Choose the Standard NVM Express Controller provided by Microsoft, install it, and restart your PC.

Fix 4: Update CrystalDiskInfo (Version 9.9.0+)

If you are running an older edition of the software, it literally might not have the definition file required to read your drive’s hardware ID.

Ensure you have downloaded the latest Standard Edition (Version 9.9.0 or newer). The developer frequently pushes updates specifically to expand the database for newly released controllers and external USB bridge chips.

The Verdict

Seeing an “Axc” or “Unknown” status can be jarring, but it is purely a software translation issue. If Windows Disk Management lets you format the drive and you can transfer files at normal speeds, your hardware is perfectly healthy. Following the steps above to switch your controller mode or update your storage drivers will get your CrystalDiskInfo dashboard back to displaying beautiful, blue “Good” metrics in no time!

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