Monitor turns off while gaming!

My monitor randomly shuts down when playing modern warfare 3 and says "no dvi signal". The computer still remains on and I have to force it to shut down. This used to also happen with cod2 but i just deleted it. All other games like crysis and prototype work on the computer no problem. I also noticed it takes longer for the monitor to turn off when playing in safe mode then on maxed settings. The monitor also makes a buzzing nsound on some of the games especially cod2. I have checked the tempetures and everything seems to be working well. Any help is appreciated!!

My Specs:
CyberpowerPC Gamer Xtreme 1320LQ Desktop PC
Intel Core i7 2600K(3.40GHz)
8GB DDR3
2TB HDD Capacity
NVIDIA GeForce GTX 570 1.2GB
Windows 7 Home Premium 64-bit
Power Supply 950W
Motherboard: Intel Z68

 

I would try another DVI cable first if you can. It's a process of elimination. Since you have a new machine at least you can get warranty work done. A buzzing monitor is problematic, what's your refresh rate set at?