I have a Nvidia Surround setup with 3 Acer H236HL monitors, two connected via DVI and one via HDMI to a GTX 970. The two connected with DVI display pretty much the same colours and blacks, but the one connected via HDMI displays slightly lighter colours and more of a grey instead of black. When the screen saver is running it's really apparent. Is this common with different connections or a defect in the monitor itself perhaps?