Monitor on and off

this is really old, Last year, August when i came back from my tour, i opened the computer, but after a while my monitor power button suddenly busted (i'm using samsung monitor that time and the buttons are touch screens) i suspected that it is because of the lightning because there is a storm that night, when i tried it again the monitor just shuts on and off every 5 seconds(?), i tried it to our other cpu and it also doing that on and off thing, then i switched on using our old monitor Samsung sync master, after 7-8 mos. of using it, it displays the BSOD (blue screen of death) and it is flickering, but when i reformat my cpu, it suddenly turned ok, i used the samsung (the one with touch screen buttons) again and it worked by almost a month before it happened again the random turn and off of the screen even when the background videos are still running,Now i'm using a new LG monitor for 3 mos. and i suddenly got worried on what if it happened again? what is the real problem? the monitors because they are old? the motherboard? graphics or video cards? the monitors when they turn off the background video or sound are still running.