Confused UEFI settings

I have win 8.1 pro currently installed in UEFI mode.

I have installed another hard drive and want to install Windows10 pro but use my win 8.1 as default.

My confusion on UEFI settings arises from the fact that when I installed Win 8 I set the OS Type to Win8 in UEFI settings.
Now when I install Win 10 - what do I set OS Type to - it can't be Win 8 so presumably it has to be "Other".
If I set to "Other" will this affect the loading of Win 8.1 pro?

What I ideally want to do is to unplug the Win 8.1 drive before installing Win 10 and then post install reconnect my Win 8 drive
and set first boot to Win 8. If I want to load Win10 I can press F12 and select the Win 10 drive from the list of bootable devices.

I have to say that having grown up with BIOS I find UEFI bewildering and so easy to make a mistake in the settings plus the fact that the drives must be in GPT format rather than MBR or whatever it is called.

i would say it shouldnt mater, windows 8/10 for booting its all the same is it not ? proof would be upgrading from 8/8.1 to 10, you dont make any changes, you just batter in.

leave it as 8, disconnect the 8 drive and install 10 to the second drive, then as you say set primary boot device to your 8 drive and F12 if you need. i cant see any issues other that the flag on your profile post back and let us know how you get on mate.

O.K.Thanks for the info.
I still don't understand what the function of "OS Type" does. There are 2 options in the drop down menu one is "Windows 8" the other is "Other".
What would "Other" be for?
What would happen if I had "Windows 8" for Windows 8 and then changed it to "Other" and installed Win 10 on a seperate drive. Would this affect booting Win8?

Linux but dont know what the functions are.

The OS type setting has to do with the way the operating system interacts with the UEFI and, to the best of my knowledge, makes shutdown and booting faster. The Windows 8 setting should actually say something like Windows 8 and later because when the UEFI was written for the motherboard they didn't know what the follow-on to Windows 8 was going to be. Just leave it enabled.

NavyLCDR said:

The OS type setting has to do with the way the operating system interacts with the UEFI and, to the best of my knowledge, makes shutdown and booting faster. The Windows 8 setting should actually say something like Windows 8 and later because when the UEFI was written for the motherboard they didn't know what the follow-on to Windows 8 was going to be. Just leave it enabled.

So the OS Type does have a bearing on on how Win8 and or Win 10 boots. In that case can you tell me what would be the result in my senario mentioned in post 4 above, if e.g. I installed win 8 with OS Type set as win8 and then installed Win 10 with OS Type set as Other?

Sorry to be a nuisance but I simply cannot get my head around UEFI which seems too easy to make mistakes in the correct settings especially when installing OS. I know this to be so when I installed Win 8.1 pro x64. I formated the SSD with the required GPT format for UEFI and installing Win 8.1 with USB stick found that after installation there was no UEFI partition and though it would boot OK, I got BSOD when trying to boot with F12 and selecting the SSD with Win 8 on it. That is still the position now as I don't want to go through the whole process again.I have already tried to install Win 10 on a separate drive with Win 8 drive disconnected and found after installation a UEFI partition. When I reconnected the Win 8 drive I was unable to boot into either OS. So I disconnected the Win 10 drive and after agreat deal of hassle in UEFI settings managed to boot Win 8, but as I said cannot do so with F12 and selecting Win 8 from the drop down list.
Hence my initial question.

redband123 said:

So the OS Type does have a bearing on on how Win8 and or Win 10 boots. In that case can you tell me what would be the result in my senario mentioned in post 4 above, if e.g. I installed win 8 with OS Type set as win8 and then installed Win 10 with OS Type set as Other?

OK. Let's go with that plan. So what are you going to do when you want to boot to Windows 8? Go into BIOS setup and change it back to OS Type Win8? Then when you want to boot into Windows 10, go back into BIOS setup and change it back to OS Type other? And switch that setting every time you want to change the OS you boot into?

Like I stated - the features of the interaction between the UEFI (bios) and the OS that are enabled by setting the OS Type to Windows 8 are the same features that are used by Windows 10. So, why not just leave it set for Win8 and leave it alone?

MSI motherboards:

Windows 8/8.1 Feature

Before enabling this item, make sure all installed devices & utilities (hardware & software) should meet the Windows 8/8.1 requirements.

[Enabled] The system will switch to UEFI mode to meet the Windows 8/8.1 requirement. Windows 8/8.1/10

[Disabled] Disables this function. Windows 7/8/8.1/10

NavyLCDR said:

OK. Let's go with that plan. So what are you going to do when you want to boot to Windows 8? Go into BIOS setup and change it back to OS Type Win8? Then when you want to boot into Windows 10, go back into BIOS setup and change it back to OS Type other? And switch that setting every time you want to change the OS you boot into?

Like I stated - the features of the interaction between the UEFI (bios) and the OS that are enabled by setting the OS Type to Windows 8 are the same features that are used by Windows 10. So, why not just leave it set for Win8 and leave it alone?

Yes you are quite right in what you say.
I think the best thing I can do is the following:
I have already taken an image of Win 8.1 and put it on a separate disk. So will load my UEFI created USB with Win 8.1 ISO on it and do a custom install -deleting the currently installed Win 8.1 partition and selecting the unallocated partition resulting from the deletion to install Win 8.1 afresh ,assuming that the installation will create the UEFI partition. Then I can restore the image to the partition and so get myself back to how it should have been. Of course I shall modify the OS Type to Windows 8 and keep it so.
I can then install Win10 on a separate disk as I intended.

What do you think?