Convert Win7 Retail ISO to Win7 OEM ISO

A Win7 retail install disk will not work with an OEM product key. It'll install, but your Product Key would be rejected for activation.

That's because, in a file on the install disk, there is a preset value for the 'Channel' to which the licensing belongs.  In a file called ei.cfg one of the entries is called 'Channel' and the value set for that variable on a retail install disk is set as 'Retail'. For the OEM key to be accepted, that variable needs to be set to 'OEM'.

It's rather easy to fix, if you wish to make a 'roll your own' install disk to use, but you need to use a suitable third party software tool to do the job.  A suitable software tool will be one which performs the functions of:

  • Creating an .ISO file disk image from an optical disk.
  • Allowing the contents of files within that ISO image to be edited.

ISOBuster is a popular such tool:

So the procedure required is:

  • Create an ISO image of the install disk
  • Locate the file ei.cfg which is in the \sources folder on the disk
  • Alter the entry value for 'Channel' from Retail to OEM
  • Burn the altered ISO image to disk, to create a new install disk which will work with your OEM install key.

Note:  These procedures are not "supported by Microsoft" ones, despite the fact that related procedures have been mentioned in Microsoft technical blogs etc. They'll work just fine, but if you require any further assistance with them you can't expect that it'll come from the formal customer support arrangements.