ı have the system with amd 7890k ı need a new grapihc card What graphics cards can I use for dual graphics and can ı use Sapphire RX460 GDDR5 2GB or msi gtx 1050 ti
You do not need to be concerned with dual graphics if you're getting a graphics card which is much more capable than your APU graphics. Dual graphics is used to give a relatively weak APU a slight graphics boost and works best when your APU and discrete GPU are close in specs and performance.
Given the overall performance difference between the 460 and 1050ti in various games I'd lean towards the latter. The 1050ti is somewhat more powerful than the 1050 which competes with the 460 and 560. At that point you're using an Nvidia card so there's no point in thinking about Dual Graphics anyways.