Question Second screen flickers when trying to OC

May 9, 2019
My system :
CPU - i5 4690k 4.4ghz
MB - Asrock z97 anniversary
Ram - 2x8 Kingston Hyper X Fury 1886mhz
600W Fortron psu
1st monitor - 1440p 144hz
2nd monitor - 1080p 60hz
And my gpu is Sapphire r9 280x vapor-x tri-x edition (1000/1500 stock)
So my problem is when i try to overclock the gpu. My 2nd monitor starts to flicker like crazy but only when the card is not at load. When i start a game for example it stops the flickering. And this happens even when i push it from 1000 to 1001 or from 1500 to 1501. The problem is not in the psu or the psu cables,not in the cooling, not in the hdmi cable and its not getting hotter than 65C at load. I've had this problem for almost a years now and i can't stand this any more. My Drivers are always up to date. Before that i was running 1100/1600 24/7 with no problems but suddenly it started doing that. I've reinstalled Windows a few times, tried a few versions and it didn't help. For overclocking software i'm using AMD OverDrive or Msi Afterburner. It's the same with both

Sorry, my English is not the best. :)