Question Green flashing horizontal lines when both monitors are set up and I start a game ?

[doctorAsia]

Hi, and thanks for any help.

Here's my setup: I plugged my first monitor using the HDMI port into my videocard. I plugged my second monitor into the videocard using using a male Display Port to female HDMi adapter cable (my inputs to my monitor are VGA and HDMI and my inputs for GPU are HDMI, DisplayPort, DVI-I, DVI-D).

Everything seems to run fine, except when i start a game I get multiple persistent flashing green horizontal lines on both of my monitors. This is a game from 2003, so it's not demanding. This doesn't happen when I'm not playing games. The green lines persist even after I closed the game and requires a restart in order for them to got away. I've noticed that whether I plug OUT the first monitor (the hdmi one) or the second one (adapted DisplayPort) the green lines disappear.

Here's my specs:

GPU: Radeon R9 380 GAMING 2G https://www.msi.com/Graphics-Card/R9-380-GAMING-2G/Specification
Monitors x2: 1920 x 1080 60 HZ https://www.amazon.com/Dell-SE2717H-KYKMD-LED-Lit-Monitor/dp/B01IOO4TDM
Motherboard:H81M-P33 https://www.msi.com/Motherboard/H81M-P33/Specification
Windows 10 x64

What I have tried: turned on Radeon Chill to limit fps to 60 and turned on Radeon Enhanced Sync (some form of vsync). After doing this, I opened another game (Team Fortress 2) and noticed that the game was screen tearing, so i turned on Vsync in the game's settings. Now the green lines are back, but the screen tearing is gone.

I also have to mention that up until this point I used to have my second monitor plugged into my cpu integrated graphics and I never saw green lines. My theory at this point is that my GPU doesn't support 2 monitors at this resolution (1920x1080) at the same time. I also saw this interesting bit in the GPU spec:

HDMI Connectors : 1 (version 1.4a)Max Resolution: 4096x2160 @24 Hz (1.4a)
DisplayPort : 1 (version 1.2)Max Resolution: 4096x2160 @60 Hz

which makes me wonder if my monitors are running at desynched rates or something (I have no idea)

What is your advice? Would a different converter perform better? Why is this happening?

Thanks again for any help.

Edit: i have the 2G memory videocard, not 4.

2ndEdit: I also checked and all my drivers are up to date.

 

[Fix_that_Glitch]

Cheapest troubleshoot would be to replace video cables and go from there.