Yiannopoufish :
I've tried to find the answer to this question but I still do not know. Please can somebody just give me an answer with no added confusing stuff? The OEM was pre-installed on this pre-built PC and I want to upgrade it to a retail copy so I can upgrade my CPU without having to reinstall Windows.
Thanks in advance
Yes, you can upgrade to a Windows 10 retail from an OEM.
Just go to the Control Panel, click on System and click Change product key link.
Type or copy the new product key.
Did you know that changing the CPU will not affect activation?
And even if you make enough changes (motherboard, CPU, GPU, etc) to prompt reactivation you can use chat support to get it reactivated. At least I have done several times after replacing motherboard + GPU or motherboard + RAM + CPU.