13thmonkey :
What if the bios is slightly different and the driver uses that information.
Windows doesn't care about the BIOS, it cares about the PCIe GUID which it uses to match hardware with existing driver profiles to allow multiples of any hardware to exist concurrently on the same computer. Different cards even of the exact same model have different GUIDs and will get separate driver profiles.
If you get crashes from swapping out different GPUs using universal drivers, then something in the driver stack might not be saving/loading stuff that should be GUID-specific to/from GUID-specific storage.
Are you using generic universal drivers from Nvidia or customized AiB drivers and utilities? I wouldn't be surprised if customized drivers were more likely to freak out on hardware swaps, such as by omitting vendor checks before attempting to access vendor-specific board features.