Quick question about UEFI before installing Windows 10

rivre · 23 Jun 2016

I'm preparing to install Windows 10 on my new PC. The motherboard is the Gigabyte Z170x Gaming 7. I have a quick question about a UEFI setting before I begin:

Under "storage boot option control" in the UEFI, I have these options:

- Legacy only (default)
- UEFI Only
- Disabled

I was told in the forums to make sure I install Windows 10 in UEFI mode. Gigabyte told me this board only supports UEFI - there's no legacy BIOS. Maybe I'm a bit confused. What is the "storage boot option control" for? Should I leave that on "Legacy only " or should I set it to "UEFI Only" for Windows 10?

Also, under CSM support:
Enables or disables UEFI CSM (Compatibility Support Module) to support a legacy PC boot process.
- Enabled - enables UEFI CSM (default)
- Disabled - disables UEFI CSM and supports UEFI BIOS boot process only.

Which one should I select? I already have "Windows 8/10" selected under "Windows 8/10" features. I'm using a 2TB mechanical drive, no SSD.

fdegrove · 23 Jun 2016

Hi,

That MB supports both UEFI and BIOS mode . Hence CSM (Compatible System Mode or something along those lines)

For installing W10 with UEFI only disable CSM.
How you set boot control will depend on the media you are going to use for installation. Normally W10 installation media supports both legacy and UEFI modes.
You could try setting it to UEFI only and if it boots you're good to go.

Cheers,

rivre · 23 Jun 2016

Thank you very much. I asked Gigabyte twice and both times they told me this motherboard supports UEFI only, not legacy BIOS. But then they told me to keep CSM enabled. She said I "have to". I was left very confused.

I want to be sure to install in UEFI mode so it sounds like I should disable CSM.

rivre · 23 Jun 2016

OK so I disabled CSM and the other options disappeared. I guess I'm all set unless I run into a boot issue.

Another quick question - should I enable "Secure Boot"? It's set to disabled by default.

fdegrove · 23 Jun 2016

Hi,

Secure boot can be enabled or disabled. It only protects the boot sector from viruses etc.
Normally I have it enabled. Can't recall what the default is on my MB.

Cheers,

rivre · 23 Jun 2016

Err, okay I'm having an issue. Now that CSM is disabled, the PC keeps booting back into the UEFI/BIOS automatically. Every time I boot up the PC it boots into the BIOS again. This just started just now when I disabled CSM. Maybe that should be left enabled then? Confused.

fdegrove · 23 Jun 2016

Hi,

Yes, that's actually quite normal as it has detected an unexpected change and requires some confirmation.

Enter the bios and enable CSM and disable Secure boot.
That should break the loop. If that works you can try disabling CSM again and try to boot from your install media.

Cheers,

topgundcp · 23 Jun 2016

Make sure you have only one HD/SSD connected to your PC so temporarily disconnect the rest during installation.

Disable CSM & Disable Secure boot.
Find out which function key to invoke Boot Menu then boot up your PC with the Installation USB connected.
Boot up your PC and keep tapping with the Function key in step 3 to display the Boot Menu.
From Boot Menu, there are 2 options for Legacy(MBR) and UEFI. Select UEFI
On the first screen, hold down SHIFT key and press F10, type:
dispart
select disk 0
clean
exit
exit
Click Next, select Customize then continue the installation

rivre · 23 Jun 2016

topgundcp said:

On the first screen, hold down SHIFT key and press F10, type:
dispart
select disk 0
clean
exit
exit
Click Next, select Customize then continue the installation

Thanks but what does this do?

rivre · 23 Jun 2016

fdegrove said:

Hi,

Yes, that's actually quite normal as it has detected an unexpected change and requires some confirmation.

Enter the bios and enable CSM and disable Secure boot.
That should break the loop. If that works you can try disabling CSM again and try to boot from your install media.

Cheers,

If I enable CSM I don't have an option to disable Secure Boot. The Secure Boot option is only available if I disable CSM.

With CSM disabled, I now have this:

System Mode State: Setup
Secure Boot State: Disabled.

As soon as I disable CMS though I'm stuck int he loop. It keeps booting to the BIOS. If I enable CSM the option the secure boot option disappears but then the loop is broken and it skips the BIOS upon reboot.

Note I don't have my Windows 10 USB thumb drive plugged in yet - I was trying to make sure my settings were correct before I plugged in my install media.