I built a new gaming PC a couple days ago w/o a graphics card (I'm waiting for one). It has been working just fine, except a few times when I turned it on it said no signal on the monitor but unplugging the power seemed to fix it those times, but nothing is working this time. The PC lights turn on and the fans spin, but it says no signal (I'm using Displayport). I tried turning the PSU on and off and same with the power strip. I don't know what to do!!! HELP!!!!!!!!!!!!!!!