monitor shutting off not sure if its my graphics card or the monitor

[rustbombs]

Today I got a new samsung 27" monitor and whenever I run a game the monitor will shut off then back on about every 15-20 seconds. I have a DVI to VGA (VGA into the CPU and DVI into the monitor) plugged in, and am using a 1920x1080 resolution. I have tried lowering the resolution to 1280x720 and it still shuts off. my old monitor is an 18.5" and it runs perfectly on my CPU. my CPU is an HP Compaq 8000 Elite USFF Desktop Core 2 Duo E8500 3.16GHz 8GB 250GB w/ Win 7. I am not a big computer guy, and cant tell if this is because of my CPU graphics card not being able to handle the high resloution or the Monitor itself. all help is appreciated. thanks

 

[GokAy]

Try un-plugging PC and monior, and then re-plugging.
Then load defaults in BIOS.
Check if monitor is still being detected as the old one.

New monitor, can be defected, try on another PC/laptop.