Q: Dark screen on Mac Mini (late '14) + LG 29" 29EB73-P

I try connect my mac mini to LG using miniDP to DP cable, the brightness look shows down. After using HDMI and setup PBP screen is possible to see the difference, left is HDMI and right is DP.

I change the DP mode to 1.2 and the mode to PC

What I tried to fix:

- Update mac mini to 10.11.6

- Clean NVRAM

- Change the cable (3x)

- Change monitor to another with DP to test the cables (works great in Dell Monitor at work)

- Force RGB Mode

- Check brightness is max for HDMI/DP

- Connect Ubuntu 16.04.2/Windows 10 to DP (works)

- Install Windows 10 on Mac mini and connect to DP (works)