Hi
Is the USB win 8 the same one used to previously to install windows ?
Or was it a recovery disk created on the PC?
The manufacturers Oem win 8 is looking for the motherboard and data embedded in it. Which identifies the make & model but not serial number
Microsoft system builder OEM and retail windows use the key typed in which should match the key on the label (COA)
There are a number of programs which can report the windows key from the c:\windows folder
If a manufacturers Oem windows the embedded key will not match key on label
Eg nirsoft.net. Produkey
Regards
Mike Barnes