I'd like to ask if it's safe to use a PSU to just power CCTV Cameras and recorder (which uses 12v) without using a computer. (are there things i should watch out if i do this like using dummy loads ...

Power supplies are simple, right? Just figure out how much power draw all your computer parts use, get one with a few more watts, and call it a day. Wrong! In addition to creature comforts like ...