zanic1234 :
so which graphic card is best for i5 9600k
The i5-9600K is fast enough to support up to the fastest GPUs available (RTX 2080 Ti, RTX Titan, etc.)
It's a rule of thumb to budget 2x the cost of your CPU for your GPU. So if the i5-9600K costs $250 you will want to spend around $500 on a GPU such as the RTX 2070. But you could get an RTX 2060 and still be doing well with your build. If you can't afford that much, then downgrade the CPU so you can get a faster GPU.