dilema of replacing motherboard before activating windows first time

i see i didn't make myself clear enough.
It should be: "Since our computers have 8gb of ram and we would like to use it all" .
I am pretty much aware of 32 bit system limitations, and how ram works in 32 and 64 bit oe's on the same computer.
I would rather avoid using 32 bit operating system nowdays in general, because ...well compatybility to new software rather swing this way (virtual machines, and stuff would not run on 32 bit system or at least not the latest versions)
However i think i found rather silly solution to my windows installation problem.
Since i have digital licencing already registered with microsoft servers for all my computers, meaning my pc would activate if windows activation servers see it with generic *-*-*-3V66T key. I first tryed to launch windows 10 setup in windows 7 and use this key, didn't acept it. Windows 10 installation didn't accept my oem keys either.
I came here, make a fus and start thinking myself.
Later i went online and serched for "free windows 10 key 100% working" got a pro version, went offline with the computer in question , Then windows 10 installer updated win7 to 10 and accepted this key. last step i did was changing it in windows 10 back to generic *-*-*-3V66T so it would activate from digital licencing and not even try activating from that wierd "free" key.
So far it worked, but i run out of time at work, so i didn't go online with the pc yet, we will se on monday if they activate, but i have strong feeling they will. And that would also be a good base for a restore image for a whole classroom.

Yes i fully understand your point, but i couldn't do it this way. Antivirus we have require internet connection to be even installed, so do corel, plus i had to download few programs from internet anyway, so it was kind of offline-online-offline kind of setup
I am kind of in a point you would be with fresh win 10 install offline only with all the stuff from windows 7 already installed. which include
antyvirus software, ms office, libre office, vmwere workstation, browsers, corel, gimp, blender, notepad++, codeblox with compiler, inkscape, and probably something more because i don't remember all of the programs we use in clases.
Either way now i will roll it out as a disk image and deploy with clonezilla or something as a backup/restore image.

however i can tell you this, by chosing "i don't have a key" option in fresh windows 10 setup you have 2 scenarios
1 if the key is already embeded into your motherboard by the computer maker windows will just read that
2 if you don't have it embeded windows setup will use generic update key for your selected version and pull digital licence from the microsoft servers to activate first time being on internet
either way key in firmware or motherboard serial number must match data on ms servers to activate
This was the whole reason of me creating this topic in the first place, to find out how it operate and understand it.

With win 7 you don't need a key at all to install or run system, but windows 7 do not have a generic update key like win 10 does, it just runs without one. And this is why i couldn't upgrade 7 to 10 in place saving all the settings and programs without punching in some windows 10 key that setup would accept, i could remove later. Because windows 10 setup from a host os simply won't let you past key checking stage. Either it reads it from your system, or demands a key from you directly and there is no skip option at this point.

i must say that my method while being madness, worked.

thanks everyone for help

Can you explain more clearly?

Superfly said:

That's a loop-hole relating to the legit transfer of OEM licences in places like Germany - it only worked with Win 10 OEM licences in my tests - but be that as it may, it is a EULA transgression that MS has not been able to/want to plug.

I don't think MSFT share prices are going to take a dip because if it, OEM's will most likely, but then they rip Joe Public off most times as it is, so.....