it can be your: CPU, Motherbord, RAM memory, GPU, Kabels, PSU ect.
You can try to give more information!
Thanks to everyone who wants to help. I solved the problem by giving back my display card.
This black screen problem is AMD's chronic problem. If they do not correct it, many customers will be lost. I hope Moderator will be able to deliver this problem to AMD's engineers. I do not believe that they will tell their engineers, but let's see.
Thank you moderatör.
8 GB DDR 4 2400 mhz cl 15 RAM
500 watt +bronz
240 GB SSD
sapphire R7 260x