System Prep Windows 8.1 for motherboard upgrade?

I've been trying to decide whether to upgrade my motherboard for the last several months. Since I have been having issues with dropped Ethernet connections lately and after all the troubleshooting (installing Windows 10 preview build, modem swap, etc.), as of now, there is currently a 70% chance that I will upgrade the motherboard. This is due to a possible faulty Ethernet connection. The only thing that now stands in the way is extensive testing of a wireless network connection. If I do go with the motherboard swap, then I need to figure out if it's possible to set up Windows to deactivate before the upgrade and reactivate after the upgrade without reinstalling everything. I will upgrade from my ASRock Z97M Pro4 to an ASUS Sabertooth Z97 MARK S. Will swapping motherboard brands complicate the process due to needing new ASUS drivers? Also, I will upgrade Windows 8.1 to Windows 10 and migrate it to a new Samsung 850 Pro SSD. (I will be installing Windows 7 on my old SSD in indirect dual-boot configuration for better compatibility with legacy programs and games and as a backup OS.)
 
Solution
No need to uninstall any old drivers.

I suppose you can set up a dual boot situation, but that would entail needing both drives to boot either.
If you would be happy to change the boot order in bios whenever you wanted to change, that could be done also.

As to windows 10, it is not clear to me exactly what will happen. I think the windows 10 free upgrade will invalidate the old os, so that may not be what you want to do day one.
I would expect some bugs also. Unless you have a compelling rason for windows 10, I would wait for a fair while before converting.
Your chances of booting with your old windows drive are very good because the Z97 chipset is common to both.
Assuming you are successful, you will only need to install the drivers that come with your new motherboard cd.

I suggest you first buy your Samsung 850 pro and use the samsung ssd migration utility to copy your os to it.
In the event that something goes bad, you still have your old os to be able to boot.

Document your current activation code before you do anything.

With the new motherboard, you may need to do a phone activation. The key question is to say no when asked if this copy of windows is used anywhere else.

 
I have the product key which is included with my Windows 8.1 retail DVD. Do I need to manually uninstall my ASRock drivers (ASRock LAN driver is the only one I could think of)? If so, since I don't see it in Programs and Features, how would I do it? Also, since I can migrate Windows 8.1 to the new drive, is it safe to install a Windows 7 license to the old drive assuming that I disconnect the Windows 8.1 drive first, then boot with both drives connected? Also, I have Windows 10 preview on my HDD. Do I need to delete that custom partition before upgrading Windows 8.1 to Windows 10? Or delete it before installing the new motherboard?
 
No need to uninstall any old drivers.

I suppose you can set up a dual boot situation, but that would entail needing both drives to boot either.
If you would be happy to change the boot order in bios whenever you wanted to change, that could be done also.

As to windows 10, it is not clear to me exactly what will happen. I think the windows 10 free upgrade will invalidate the old os, so that may not be what you want to do day one.
I would expect some bugs also. Unless you have a compelling rason for windows 10, I would wait for a fair while before converting.
 
Solution
OK, thanks. I guess for now, I can hold off on the reservation until this all gets sorted out, then I'll upgrade to Windows 10 at a later time. Meanwhile, I'll have Windows 7 to use if I need it. If I install Windows 7 when Windows 8.1 is already installed on the current drive, I assume it's correct that I need to disconnect the Windows 8.1 drive, connect the Windows 7 drive, install Windows 7, reconnect the Windows 8.1 drive, and the PC will boot to Windows 8.1 by default, correct? But if I keep the Windows 10 insider preview on the HDD, the PC seems to want to boot to it by default as it does now, even if I change the boot priority in the UEFI BIOS. Also, is it a good idea to get Windows 7 Professional rather than Home Premium? XP mode could be useful, though Microsoft no longer supports it.