If you are getting normal benchmarks in games, and the system is not crashing, the cards are OK. Windows updates do like to mess with video drivers, especially Windows 10 if that is what you are using. Take a look at your update list and see if anything was installed during the time the issue happened.
I've deleted any recent windows updates, no resolve .
Testing each card on 3D Mark shows that they are running almost identically so I think the cards are okay.
I have two hard drives that I have ran games from and that doesn't make a difference so I don't think it's my hard drives.
I'm out of ideas
I'm thinking format next?