Hello, Few days ago I bought the ASUS Radeon RX 580 graphics card. Of course, I first completely uninstalled the old drivers using the AMD utility, then downloaded and installed new ones, but I started to notice some difficulties. When watching a fullscreen series (via Plex, BSPlayer, VLC, etc.) (I only notice in the fullscreen, if the window is smaller, the video is running smoothly), the playback is abnormally lagging, but only when the window is active, ie when I click on the desktop on the second monitor or another application, lagging stops. I registered the same problem while playing the League of Legends in the borderless window or in The Walking Dead: The New Frontier (I do not know if this is relevant information, I'd rather mention it). Temperatures are OK (CPU ~ 45 °, GPU ~ 55 °). It is important to note that this lagging is happening only on the main monitor, when I move the video on the secondary monitor, everything is fine. I wondered if problem isnt in cables. I disconnected the secondary monitor (BenQ G2420HDBL, 60hz), the main monitor (AOC G2770PF, 144hz, FreeSync) is connected by DisplayPort and since I do not have a second DP cable (or DVI) at home, I tried to connect it via HDMI- I didnt notice any lagging. Previous GPU R9 290x was connected by the same DP cable and this problem did not occur. I would mention that I remowed all OC software, the system is updated and I tried all available drivers for rx 580. So I think either I have damaged DisplayPort cable or I was lucky for a faulty piece of GPU. CPU: i7 4790k GPU: ASUS Radeon RX 580 ROG-STRIX-RX580-O8G-GAMING PSU: Fortron 750 W RAM: 16 GB DDR3 Here is a video for demonstration: //youtu. be/O8vNlVZNwpc Thank you in advance.