UEFI Enabled Install

[feetand nches]

Guys, I'm confused...again haha!

Some of these Windows 7 machines have UEFI to some extent. At least they have the option for Secure Boot and Switching Off UEFI, and just use Legacy. My issue is, when I go to install to a machine that came with Windows 7, but had the Windows 10 Upgrade, I don't know if I can chose the UEFI Entry at boot or not?

The last one I installed in Legacy, but UEFI was Enabled. The OS would not boot so I Disabled UEFI and all booted fine.

My Main Question at this point is: Is it even possible or suggested to Install from the UEFI Boot List, and therefore leave UEFI/Secure Boot Enabled? I ask because the UEFI Boot List is always Enabled even though the pc came with Windows 7. Both these machines came with Windows 7 and had Windows 10 Upgrades via the usual Forced Upgrade lol, just kidding. Whew, hope all that makes sense.

 

[samuria]

The basic idea of uefi and secure boot is the system will only boot a o/s that's registered so any virus that changes system boot files will be stopped and it prevents anyone booting another system to access the PC

 

[feetand nches]

Thanks samuria, but I understand UEFI, I just don't understand why it is Enabled on a Windows 7 machine? And, refer again to my opening post please in case you did not read it.

 

[Megahertz07]

As Samuria mentioned, with Secure Boot enabled, during boot bios look for a digital signature on on the boot loader. Win 8x, win 10 and Linux can use Secure Boot. Win 7 can't.
- You have two kinds of BIOS operation: Legacy - MBR and UEFI-GPT.
- If BIOS is set to Legacy - MBR operation, the boot sequence start on BIOS that looks for a MBR on a DISK (boot priority). From the MBR the boot sequence is transferred to a master boot loader on a Partition (same disk or not) that can call a boot menu (multi boot) that can transfer to another boot loader. For ex Grub (master boot loader) that can call Linux boot loader or windows boot loader.
- If BIOS is set to UEFI - GPT operation, the boot sequence start on BIOS that looks for a boot loader on a Fat32 partition that will call the OS on a partition. On this Fat32 partition you can have endless independent boot loaders, each one calling a different OS on different partitions (same disk or different disk).

As you can see, if BIOS is set to operate as Legacy - MBR you must have the OS on a Legacy - MBR disk and if BIOS is set to operate as UEFI - GPT you must have the OS on a UEFI - GPT disk. One isn't compatible with the other.

Win 7 64 can boot from a UEFI - GPT disk.

- BIOS should have two operations modes: Legacy - MBR OR UEFI - GPT
- Secure boot: Enabled or Disabled
- Fast boot: Enabled or Disabled

Some manufactures (like Asus) made a big mess when referring win 10 as UEFI.
So it has two operations modes: UEFI and other (UEFI = Win 10 UEFI w/ secure boot, Other = secure boot off)

When operation mode= Other you can still have:
CSM (Compatible System Mode): enabled=Legacy - MBR
CSM (Compatible System Mode): disabled= UEFI - GPT
Secure boot: Enabled or Disabled

If the original Win 7 was installed in one operation mode, when you downgrade to win 10 it will be installed on same mode.

 

[feetand nches]

The last one I installed in Legacy, but UEFI was Enabled. The OS would not boot so I Disabled UEFI and all booted fine.

I understand most of that, what I don't understand is why the last machine was UEFI Enabled, even though it had Windows 7 from the OEM, and I assume no one had messed with it, guess I should not assume.

I guess the answer is Windows 7=Secure Boot NO!