I recommend not mixing AMD with Nvidia.
You mine with one of the gpu while playing games with the other.
I am gaming for about 2-3 hours a day.
Why would you recommend not mixing? If I go the Nvidia route I would mine ETH with the RX and whatever is most profitable with the Nvidia, so two different mining programs. Do these slow each other down?
You can add the multiple gaming cards in the one rig. If it is same variant it would be works better still you can have the multiple variant cards in the rig to work it. Recent days Rx 470 and 570 cards not available in the many places in the world. I am looking for cards from the past 1 month but I did not find in the cards from the any locations in my country.
For better hashes you can have the rx 580, Nividia 1070 or 1080ti card to make a powerful rig.