I recently upgraded my motherboard from a Gigabyte 78LMT-S2p to a Gigabyte 990FXA-UD3. When I tried booting up Windows it blue-screened, and after some research I learned that it has something to do with the drivers and that the easiest solution would be to reinstall Windows 7. I also read that it is possible to get Windows running without reinstalling it, but I was unable to find any sort of guidance on how to go about that. I'm currently running Windows 7 off of a spare HDD I had, so I'm wondering if there is some way to fix the old installation from this new installation on a different drive.
The correct way to do this would have been:
The downside to this is that you need to start before you swap motherboards. In your case that means reverting to the old setup, running sysprep and then changing the motherboard again.
An other method which you already mentioned is a clean reinstallation of windows. This has the advantage of giving you a clean start with no left over cruft. Is that is worth it or not depends on you (e.g. how clean in the old install. Does it even bother you if there are left overs or do you really want a good start, etc etc. Only you can answer that part).
Typically it is hit or miss if this works, but here are the steps that have worked for me.
You'll have best luck if your new motherboard is based on a similar chipset.
If you can't install the new motherboard chipset drivers while still on the old motherboard. Try force installing them by finding .inf file, right clicking and choosing 'install form here'