New GPU problems, need help

[vladutn]

Hello everyone, i am posting on this forum first time and hopefully someone could help with my problem. I bought new RX 570 about month ago and i am getting some strange glitches on my screen. Glitches happen only when my brother is using Blender and Unreal engine editor and when i play game. Strangest thing is that while i play my game it's working fine untill i open menu. Glitches manifests as screen flicker for one or two frames and/or smudges. I dont know if it is problem with GPU or its some driver issue, it never happened with my old GTX 660. I did fresh instalation of windows 10 and installed all drivers manually  without internet. I dont know if i should send back GPU to seller because i am afraid they won't test it good enough and say that its working fine. I didn't mention that i tried to record it with Bandicam, but on video glitches dont hapen. 

My system specs:

CPU Intel i5 2500k
Motherboard Gigabyte z68xp-ud3 rev1.3
8GB Kingston HyperX
PSU Chieftec 650w