I mean, if it works, that's great, but if there is any part of the board that isn't working the way it should I'd want to make sure of what it is and that it's not something that's going to become a bigger problem later on. Motherboard issues usually don't just stay limited to one thing. When there is a problem it is usually a good idea to get it replaced while it is under warranty instead of waiting until the problem becomes bigger later and you can't get it replaced.
No, that's not what it says. The BOARD is a B660 chipset model, there wouldn't be an M.2_1 slot on there if it couldn't be used with the B660 chipset since THAT IS WHAT THE BOARD IS. LOL. There is something else going on. Do you have other add in cards installed besides graphics card?
What are your FULL hardware specifications? Thought I asked this previously but I don't see them listed anywhere.