I'm on a Mac Pro running OS X 10.9 with a NVIDIA GeForce GT 120 512 MB, and I'm using a BenQ E2420HD as a monitor.
The Problem: Every day I start my Mac in the morning, and every day the monitor has no signal the first time I start the computer. The only thing that works is to shut the Mac Pro off by holding the power button down for a few seconds. As I start it for the second time, the monitor gets a signal and everything works. That happens every day and it's very bothering, and probably also bad for the Mac Pro.
- I tried plugging the monitor cable out and in again and manually setting the input in the monitor menu — not working.
- I also reset the SMC and NVRAM — nothing changed.
- I had the monitor connected via DVI-DVI and then changed to HDMI-MiniDisplayPort because I thought that might help — nope.
This problem occurred in OS X 10.8 as well as it does now in 10.9. It's very frustrating!