Using Multiple P2715Q Monitors on Mac Pro - WEIRD.

This is one of those problems that just makes no sense to me at all. I'm the go to troubleshooter in our office, but I'm stumped. (3) P2715Q Monitors set up on a Mac Pro. About 10% of the time, when I wake them up - monitor 2 (in a 1,2,3 set up). Doesn't come on. I swapped monitor 2 to the 1 spot but kept all the cables the same. (in other words, the cables that were connected to the broken monitor are not connected to a working monitor) Now #1 doesn't wake up 10% of the time. This verifies it's not the cables or port or computer. Only this monitor. Here's the kicker, I'm on my third monitor from dell. When the second one did the same thing, I thought, "This one is worse than the first!" So I sent it back and I'm on number three. Again, it's only 10% of the time, but the only way to make it work is to swivel it around, unplug and replug it (power button does nothing). It's not horrible, but it is a very expensive monitor and I've love for it to be consistent. Any thoughts besides "first world problem!" Thanks pros!