Cannot install windows 8 pro on a windows 8 machine

I have a windows 8 pro system builders disk and key and a computer that has windows 8 standard pre-installed.
When i wipe the computer and install from the windows 8 pro key the installer uses the computer's bios key (the standard windows 8 key) which forces the install to be a standard 8 install instead of a Pro install.

How can i prevent the installer from using the bios key?????

I would of thought using a system builders license on an OEM computer would be a breach of the licence terms and as such we could not talk about it here.

However in the interest of science it is an interesting problem, I think I'd try an Unattend.txt answer file with the new key in and see if that worked (I've not made one since the XP days so don't ask me how lol )

To upgrade Windows 8 core, you need to use the Pro Pack.

To upgrade to Pro Pack
No install files needed.
Only the Upgrade key is need.

http://www.eightforums.com/tutorials/6673-add-features-windows-8-a.html
or
use the Windows 8 Pro OEM full version.

To upgrade to Pro OEM full version.
No install files needed.
Only the Product key is need.
http://www.eightforums.com/tutorials/6673-add-features-windows-8-a.html