I have had a U2414H for a few months now and with certain programs it seems to not refresh when the image changes. For example, on Titanfall, when the game starts the monitor does not go into sleep mode, but displays no image. The only way to get an image to appear is by turning the screen on and off again, with the same problem occuring if I alt+tab away from the program. Also the problem occurs in other full screen applications such as 3DMark.
I've tried both HDMI ports and both the HDMI and DVI output on my GTX560Ti but have the same issue. I've tried the setup on a different PC with the same results. The problem however is not apparent on another monitor I tested it with, making me think the issue is with the monitor rather than the GPU.