As it seems that you guys are discussion regarding Dell S series monitor I would like to inform a design problem in those monitors.
Couple of weeks ago I bought S2240L - the smaller sibling of S2440L. the issue is with how the LCD Panel (glass + LCD Screen) is mounted on the body/housing. the S series monitors has edge to edge glass, there is a tiny gap(1mm may be) between the housing and the screen. also the screen is not sturdily attached. because of this if you apply a little pressure (say when cleaning or taping on the screen ) the screen moves(<1mm). I had initially thought that it was a manufacturing defect thinking whole screen was not bolted properly, but it turned out that other piece which my vendor opened to check also had the same issue. I think its by design.. but other than that there is no complaint at all. the monitor is outstanding.
As for gaming.. I can check it over the weekend with BF3.