How to make OEM Windows 7 legal after motherboard failure.

[Geek-9pm]

Pardon me.
This has been hasted around over and over again.
But I forget things, Especially things that are not well-defined.

My old Dell bite the dust. That was some months ago.   It had a  OEM Windows 7 pro 64 bit. I still have the DVD and product key.

I got another Dell computer and it runs Windows 10 32 bit. I also put Windows XP on it. Also I put Ubuntu on it. MBR.

I forgot about the Windows 7 DVD that goes with the old failed Dell.

Now I just got  another computer a week ago, a Gateway, with Windows 10. I thought it would be nice to have Windows 7 again, so after a lot of work I made it dual boot Windows 7 and Windows 10. GPT.

No I am not tying to cheat anybody. My old OEM machine is stone dead. I should know better,  but I forgot. It is asking me to activate Windows 7. So I put in my old product key and it says that it is not right.

A search on the Internet gives conflicting answers. One claims to be from Microsoft and it says that I can transfer the OEM license to a replacement motherboard. But apparently that is not true or else there is some odd way of doing it.

This is not a critical issue. I don't need Windows 7. Actually, I do have another legal copy I might try, but it would be a hassle to do the install all over again. It would be a lot easier, I think, if there was some way I can legalize the install I just made. I am sure I can not use the other product key, they are different versions of Windows 7.

Can I call Microsoft support and beg them for an exception?

Here is what I have legally.
Two DVDs with Windows 7 and respective product keys.
Two computers, each has legal Windows 10.

I would like to have  at least one PC  boot Windows 7 whenever I like.
No way am I trying to sell either of these computers.

Any thoughts?

[gameperson]

It sounds to me that you can, but read this first.
https://www.howtogeek.com/261053/when-can-you-move-a-windows-license-to-a-new-pc/

You may have to call microsoft and explain what happened. The worst case scenerio is that you'd have to use a brand new windows 7 key.

[Geek-9pm]

Thank you. I t has been over a year and I did find legal way to license a replacement.
The link yu provide is very good. There are a umber of legal ways to resolve the problem. The one rule is that yu never can have one license working on two good PCs at the same time. But you do have to call Microsoft on the phone and get help from a representative.