The way I'd handle this is to build this computer with the 560 Ti, see what games they play and how those games perform. You might not need a new videocard. You mean RX 580 right? That card would be much better, it's no comparison. The 8350 would be the limiting factor when paired with the 580 but even so the games would look and run much better IF the games are the kind that can use that videocard's power.