Using the included DP cables on both of mine and no flickering seen at all since getting them last week. I haven't turned them up to 165Hz mainly because I don't see the point, there's no way I'll see a difference between 144 and 165, so I just leave it at the default.
Not sure if it's related, but I read about some power save issues with this monitor in Amazon reviews when connected via DP. The basic suggestion is to turn off the power save feature on the monitor itself...go into the options that let you adjust brightness, contrast, color, etc., and in the...
Dell currently has a sale on their monitors, buy one get another half off (lasts until 10/31/16, FYI). It just so happened to coincide with my starting to look for a 1440p/144Hz monitor, as I was already looking at the S2417DF for its added G-Sync capability. That sale essentially sold me on...