M.2 Drive only visible when CSM is enabled

[eddified]

I have the Gigabyte Z370 Aorus Gaming Wifi Board. https://www.gigabyte.com/Motherboard/Z370-AORUS-GAMING-WIFI-rev-10#kf

If I disable CSM, the M.2 drive ( ADATA PCIe SSD: https://www.amazon.com/gp/product/B075Y23Y37/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1 ) no longer appears in the BIOS, and it won't boot.

Can someone please explain what's going on regarding CSM and the M.2 drive?

 

[Calvin7]

NVME SSDs do not appear within the BIOS until Windows creates the system partition with the EFI Boot Sector. Your M.2 SSD contains UEFI driver information within the firmware. By disabling the CSM module Windows will read and utilize the M.2-specific UEFI driver.

1- The M.2 drive has to be the only drive installed.

2 - Go into the bios, under the boot tab there is an option for CSM, make sure it is disabled.

3 - Insert a USB memory stick with a UEFI bootable ISO of Windows 10 on it, USB3 is quicker but USB2 works also. A Windows DVD won’t work unless you’ve created your own UEFI Bootable DVD.

How to create a bootable UEFI USB drive with Windows 10 Setup
https://winaero.com/blog/how-to-create-a-bootable-uefi-usb-drive-with-windows-10-setup/

4 - Reboot and install will begin

 

[eddified]

NVME SSDs do not appear within the BIOS until Windows creates the system partition with the EFI Boot Sector. Your M.2 SSD contains UEFI driver information within the firmware. By disabling the CSM module Windows will read and utilize the M.2-specific UEFI driver.

1- The M.2 drive has to be the only drive installed.

2 - Go into the bios, under the boot tab there is an option for CSM, make sure it is disabled.

3 - Insert a USB memory stick with a UEFI bootable ISO of Windows 10 on it, USB3 is quicker but USB2 works also. A Windows DVD won’t work unless you’ve created your own UEFI Bootable DVD.

How to create a bootable UEFI USB drive with Windows 10 Setup
https://winaero.com/blog/how-to-create-a-bootable-uefi-usb-drive-with-windows-10-setup/

4 - Reboot and install will begin

I used a bootable Windows 10 USB drive to install Windows 10 on the M.2 SSD, and the SSD was the only non-removable drive installed at the time. I must have had CSM enabled at the time I installed Windows though. The M.2 SSD has a hidden partition, about 500MB in size, at the start of the drive. This to me hints that it is using UEFI to boot, but I'm really not sure since the CSM module is still enabled.

Given that I'm booting Windows 10 off the M.2 PCIe SSD currently with CSM enabled, do you think I would get better performance by turning CSM off and re-installing Windows 10? What mode is it using now, do you think?

 

[eddified]

I forgot to supply this information: when CSM is enabled, the following three options are available (they disappear entirely when CSM is disabled):

• 
  ■ "LAN PXE Boot Option ROM". Current selected value: Disabled. Other possible setting: Enabled.
  
  ■ "Storage Boot Option Control". Currently selected value: UEFI. Other possible settings: "Do Not Launch", and "Legacy".
  
  ■ "Other PCI devices". Current selected value: UEFI. Other possible settings: "Do Not Launch", and "Legacy".
  

 

[t0st4r]

If you are in Windows look in with style your windows Partition is. If its MBR you only see it with csm support.
If you want to change your patition style to GPT: https://docs.microsoft.com/de-de/windows/deployment/mbr-to-gpt

 

[karenjoly]

Confirm the partition style of the M2. Is it MBR or UEFI ? This is displayed when the drive is selected in Device Manager, right click/properties/volume/populate/partition style.