I have Windows 11 installed on the first M.2 slot of an MSI PRO Z790-P WIFI DDR4 motherboard, along with several internal storage drives. I installed another M.2 drive, formatted it, and immediately noticed severe sluggishness and very long loading times. After removing the new drive, the computer usually hangs at the MSI startup screen with the spinning circle, then may get stuck on "Preparing Automatic Repair." Occasionally it reaches Windows, but the system is still so slow that programs and shutdowns can take several minutes.
I have disabled fast boot in the firmware, disconnected all USB devices, and reset the JBAT1 pins several times. The BIOS was updated about two months ago. Could the additional M.2 slot be disabling or conflicting with some SATA ports, or could the installation have damaged the boot configuration or another drive? What should I check before attempting more hardware work?
2 Answers
The symptoms could be caused by a failing or intermittently detected drive, a SATA/M.2 lane-sharing conflict, or a damaged Windows boot configuration. Don’t keep trying to boot repeatedly while all the drives are attached. Confirm that the Windows drive is detected consistently in UEFI and that Windows Boot Manager is first in the boot order. If it still hangs with only the boot drive connected, use Windows recovery from an installation USB to run Startup Repair and check the drive’s health. Back up important files immediately if you manage to get into Windows.
Start by powering the system down and removing the newly installed M.2 drive completely. Then disconnect every secondary SATA and storage drive, leaving only the Windows boot drive connected. Check whether the system boots normally that way. If it does, reconnect the other drives one at a time and verify that each appears correctly in the firmware. The motherboard manual should also show whether using that M.2 slot disables particular SATA ports or changes their configuration.
The system was fine before the new drive was installed, so I’ll test it with only the Windows drive connected and then add the others back individually.

A BIOS reset will not fix a physically failing drive, so checking the boot drive and disconnecting the other storage devices is more useful than repeatedly clearing the settings.