S2722QC, DP to HDMI cable , 4K 30Hz max

Hello everyone. So, i have a problem with Dell S2722QC monitor. I can only have 30Hz on 4K resolution. but when i switch to 1440p then i can reach 60Hz. I connect the monitor with a display port cable from graphic card to hdmi on monitor. The question is: should i buy another maybe more reliable display port cable, and if yes which model, or it is some kind of display setting that i need to do? Thank you in advance.

Graphic card: AMD RADEON R9 FURY SERIES (4096MB)

Display port model: Powertech cable displayPortmale-HDMI male 2m with Display port 1.2 and HDMI port 2.0.