UEFI installation question

Hello all, I was wondering if it is possible to install a Win 8.1 OS (Core to Pro) from an ISO image that is different than the one associated with the UEFI code on an OEM system. Does the UEFI firmware and Microsoft combo strictly limit you to the OS shipped with the unit. My comp seems to be UEFI (can't change this in BIOS) only no Legacy. Also side question: when installing ISO from a USB drive are there any issues with using USB 3.0 over USB 2.0. New to OEM units so any advice/help is appreciated.

Yes you can install Pro if you have a Pro product key.
USB 3.0 is not recognized in your BIOS/UEFI shouldn't matter main thing to understand is that it needs to be formatted Fat 32 See the tutorials for UEFI Install you won't have any issues

And it has to be 64 bit software - UEFI -GPT is only supports x64

Depends on the install media used. Example, if I use my MSDN ISO it will read the embedded key in my laptops BIOS and install Core automatically. The embedded key in my laptop is for 8.0 Core. To go right to Pro I have to add a PID.txt file with the Pro key to the install media. Or let it install Core and then use Add Features to upgrade to Pro. My MSDN ISO's are multi edition and can install Core or Pro depending on what key is used. Retail DVD's I believe work the same way. If you download install media from here, Create installation media for Windows 8.1 - Windows Help, you can get Core or Pro. If I install Core from that download on my laptop it uses the embedded key automatically. If I install Pro I get prompted to enter one.

Hello alphanumeric, thanx for reply. U seem very knowledgeable and was wondering if I might have an issue with the UEFI version that my system has. My BIOS is Insyde and when I check the BIOS it has it listed as v 1.40. I checked another post and it stated that I needed a ver. 2.0 or greater to do an UEFI install, will this be an issue? I don't imagine so as it came installed w/ win8.1 x64 but wanted to get your imput.

As far as I know, if your BIOS is UEFI, and its setup correctly, you can install Windows 8 in UEFI mode. Can you post a link to that other thread stating v 2 or greater was needed? The two laptops I have here at home came with Windows 8.0 Core, and both have UEFI BIOS. They are now both running 8.1 Pro in UEFI mode. No BIOS upgrades were required.

EDIT: Something just came up that I have to take care of. It might be a while before I get a chance to check this thread again.

No problems alpha- here's the thread. It states it at the top under requirements.
http://www.eightforums.com/tutorial...e-firmware-interface-install-windows-8-a.html

UEFI v2.0+ < I take that to mean the version of UEFI used in the BIOS not the actual BIOS version number. One has nothing to do with the other.
Protecting the pre-OS environment with UEFI - Building Windows 8 - Site Home - MSDN Blogs