It all depends of what resolution and frame rate your monitor is. The RTX cards are the 2070, 2080 and 2080 Ti and your CPU could run all of them.....depending on resolution, you may or may not get the most out of the card.
You see, at lower resolution the graphics card is doing it so easy the CPU struggles to keep up with it, but at higher resolution it's the card that has to work hard, so your CPU would be fine.
Until the cards are released and can be benchmarked, there is no way of telling you which card to get.....if you see the current cards at a bargain price, then you might be as well off getting one of them.