Typing this, have this same problem, but my monitor is a LC27HG70, worked for a few weeks, then suddenly does not turn on when pc powers on, manually clicking the menu button on the back or replugging the power socket brings the monitor back to life.   Also, shutting down the pc, waiting 5-10 minutes then powering back on has no issues, monitor will power on nicely, problem happens when pc and monitor are off for the night, so might be caused by said 4 hour sleep fucntion, i have set it to off and will report tomorrow if my monitor now turns on normally with pc powering on   Edit: 2 days have passed, monitor still does not automatically turn on, but instead when i press the menu button, the backlight starts flickering, have to switch off and on on the power brick to make the monitor functional again ... View more