Original Install was Windows 7 pro, I used Insider build 10133 to upgrade to Windows 10. Since then I been insider upto build 10240. Yesterday I downloaded Media creation tool to create an iso to do clean Install. I booted the iso via DVD drive and formated Windows 10 drive and fresh Installed Windows 10 pro. I skipped all product key steps. I am yet not activated on fresh install. Maybe its their servers.
I had a dual boot set-up with 8.1 and 10240.
8.1 downloaded the RTM/GA. I have not upgraded this yet.
10240 downloaded only some of the files for the upgrade so I clean installed the RTM/GA from the USB created from Microsoft. This wouldn't accept my 8.1 Pro key so I skipped the two screens for Key Input. When I checked the copy it was activated. WooHoo! I had to fiddle about to get the Fast/Slow ring option.
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EDIT: Using update stuck at 2% so I rebooted and it then downloaded drivers for my PC.
EDIT. The above EDIT isn't too clear. After Windows 10 was installed, I used Windows Update on the settings page. This installed drivers as shown by Device Manager. Update stuck at 2% for ages so I rebooted. WU then said it failed to install the drivers that it HAD installed. WU continued till there was no more updates
Anytime you activate a PC for the first time, a hardware hash is created on the Microsoft activation server. Along with the Product Code used on that PC. A fingerprint of that PC so to say. Any further activations with that Product Code are compared to that hash, if it matches it activates. It was done so you couldn't use the same key on more than one PC. Small hardware changes are allowed etc, so if you replaced say a video card, or hard drive it wouldn't fail activation. Swap out the motherboard and it would see it as a new PC and activation would fail. I'm not sure what they are doing with Windows 10? Sounds like the same deal only minus the Product Code part. They have recorded your free upgrade as valid on that hardware. Now you can clean install Window 10. What key you use, or even if you have to use one I don't know. It sounds like you just don't enter one at all, leave it blank and click next. That would enter a generic key most times. I haven't done a clean install on any of my systems that I've done the free upgrade on. Not yet anyway. At some point I will, but not for a while though. Not unless I have issues that force one. I need a couple of days to catch up and see where I'm at on each PC. I haven't even made up my install thumb drives yet.
I'm still waiting for the notification from MS
