Good morning. Long story short...... I bought a retail copy of W7 then upgraded it with the cheap offer for W8 when it came out via MS and subsequently again with the free W10 pro upgrade offer. I can't get the same motherboard now as it's too old (still fine for my needs though and seeing as I bought 16gb of DDR3 last month I stuffed if I'm spending almost £400 on DDR4 kit at the moment) and the replacement will obviously change the HW ID's thus from what I gather rendering my activation dead. I have looked at the activation methods in these forums and will go down one of those routes if needed but want to know if anyone thinks it's worth a call to MS when my PC is back together and playing the whole I bought a retail copy blah blah to see if they will activate W10 on the new board. Many thanks.
If your copy of Windows 7 is a non upgrade which it sounds like, you could just install Windows 10 (must be same edition, 7 Home Prem=Core/Home 10, 7 Pro=10 Pro), and just use your Windows 7 retail key when asked for the Product key in one of the setup screens. It should then activate, generating a new Digital License for the Windows 10 edition installed for that motherboard. Alternative way: The way i did a PC was to install Windows 10 Home(core), at the enter product key i just skipped/don't have one, let it all install, then once at desktop i made sure the lan was connected, went into 'PC Settings>Update & Security>Activation' then clicked on 'Change Product Key' entered the Windows 7 Home Premium key and a little while later it said Activated with a Digital License. If the W7 key is for Pro then you would install W10 Pro and the above method should work. Saves installing 7, making sure its activated then upgrade to 10 which takes time. Also saves a call to M$ and getting a stock 'Nope' sort of answer!
If you upgraded the W7 to w8 and later on to 8.1, you also should have the Retail Product Key for Windows 8?! That P-Key you could use to install 8.1 with no problem on the new MB!! After done the installation, make all available updates for Win8.1, that several times starting again!! If all that's OK and 8.1 is activated, upgrade the 8.1 to W10, and at that screen where it's asking you for a Product Key, just check the box for "I don't have a Product Key" and finish the upgrading. You should end up with an activated Windows 10. You could also use the old Windows 10 installation, which will show an un-activated w10, and use Advanced Option -->Activation from the Settings/Update and Security tabs and tell them that you had a hardware change and need to be reactivated. That works most of time! Just, you need to use your old MS Account, the same you used on the old installation. So, there shouldn't be any problem to get Windows activated normally on your new Mainboard!! Good luck!