Hello.
The response and input lag times can be a little slow for gaming on this TV. It has a 5ms response time, which is acceptable, but visible. (There will be a slight ghosting when there is fast movement.)
All in all, the answer is yes, you can use this tv for gaming with an RX480. But it may not be perfect for gaming, unlike a gaming monitor.
It will work though, and the picture will be perfect if you use an HDMI cable.