Try this: Open regedit.exe with Start Menu Search and navigate to: HKEY_LOCAL_MACHINE/Software/Microsoft/Windows/CurrentVersion/Setup/OOBE/ Change MediaBootInstall from "1" to "0". (Double-click it and then enter 0 in the dialog that appears.) Close RegEdit. Open the Start Menu again and type cmd in Start Menu search to display a shortcut to the Command Line utility. Right-click this shortcut and choose "Run as administrator." Handle the UAC prompt. In the command line window, type: slmgr /rearm Then tap ENTER and wait for the "Command completed successfully" dialog. Then, close the command line window and reboot. When Windows 7 reboots, run the Activate Windows utility, type in your product key and activate windows.
The various steps suggested in this thread so far for a clean installation using Upgrade version of Windows 8 is complicated, error-prone and unnecessary. Here is a simple way: Boot your computer from the upgrade DVD. When asked, select "Custom" as the installation type (as opposed to Upgrade). Delete any existing hard disk partitions. Start the installation. As soon as Windows starts copying files, shut down the computer (yes, this interrupts the installation, this is fine). Boot again from the upgrade DVD. Again, select "Custom" as the installation type. Again, delete any existing hard disk partitions. Proceed with the installation, this time letting it fully complete. You will be able to activate with your upgrade key just fine. The above procedure is a quicker variant of the well-known "double-install" technique. The reason it works is that the Windows 8 setup checks the existing hard disk partitions when it starts, and if there were appropriate partitions in existence when the computer booted, it will correctly flag it as an "upgrade" installation.
Would a Windows 7 installation on another HD be enough for a W8 install on a clean partition, other HD?
Short answer: NO! If you like to do a clean install using the Upgrade Product Key bought from MS directly, you should us an RTM ISO instead of the downloaded or even bought Upgrade Media/Image/ISO. While using the RTM ISO Windows 8 will be installed without to ask for the Product Key on beginning of installation, that will happens on end of installation. That will give you the choice to install which version of Windows 8 Pro you will run (32bit or 64bit) and let you d a clean install on even a new HDD without to even "look" for an previous version of Windows. If you use to install with an other HDD connected running Windows 7, the install will also go on and install an Windows Boot Manager. That's something I really don't like because if a HDD goes down, you maybe not able to even boot from the other one. Also both HDD's must be available and running all times. If you disconnect the other HDD('s) before installation, you get a clean Windows IOn stall and after connecting the HDD('s) again, you could use the BIOS Boot Manager for to chose from which OS, by chosing the related HDD from Boot Menu, you like to start.
Hmm.. that way you will have to be very attentive on every boot to press the (F10,F8.F12..) keys to choose the hard disk to boot from , if you miss it that time,then the OS from the default boot hard disk boots,and you restart from that OS then choose the other hard disk this time to boot into the required OS. so for users who switch frequently this is little not-so-easy method.But as you say it has its own advantage.
Not really! Only if you every time use to change to an different OS! If you set your "default" OS (the one you most time will use) as default in BIOS, you will only need to use the Boot Manager if you like to start up an other OS! I don't believe that will be happen by every boot! And for sure, it has it's own advantage! First: NO need of any software Boot Manager, even it's the internal one from Windows; secondly: no problem in case a HDD will fail, you could just start from an other one; third: It's a kind Hardware Boot Manager! And even if the MB goes down and you change to the same Brand and Model or to an different Computer with same Model and Brand MB, you could just start normally by using your HDD's! OK, I mainly work in corporate environment and in those networks the attached computers are mostly identical. Also we having a lot spare computers with the exact same spec available in case some goes down for what reason ever. We just moving the HDD's from one to the next one and all is working.
And this is what you get when you buy a boxed version of the update. I have used my keys on RTM ISOs (and DVDs) in English and French 32 or 64 bits and activation seems to hold. good luck!
I found this: Do a clean install with your Windows 8 upgrade USB/DVD, and enter your Windows 8 product keynumber during installation. NOTE: You can do the clean install using either a local account or Microsoft account. It doesn't matter. When the clean install is finished, if you check in System, you will see that your Windows 8 upgrade is not activated yet. Activate by Refreshing the Windows 8 Upgrade Refresh your pc under "PC Settings" When finshed, if you check in System, you will see that your Windows 8 upgrade is now activated with the product key you entered in step 2 above. You have just finished doing a clean install with an upgrade copy of Windows 8. I haven't posted 20 posts yet, so I can't post pictures or links. But just go to Google and google "fresh install windows 8 upgrade". Thereafter select the link from eightforums
I have used my key several times now and it is just a upgrade key. I had to do the registry edit one, maybe twice. Not anymore, every time I have formatted it has activated without the need to modify registry value.