This would generally be caused by a broken wire within the video cable. Green is not the only variation of this problem. Replacing the cable will most likely fix the issue.
It is a suit
A green light on your computer monitor i think means that it is on. im not sure though
If putting a known good monitor on your PC gives you a green screen, then something is broken. Probably your video card.
did you put a magnet on it? usually that is the cause no
The red CRT gun is failing
Yes, - Change the data cable of monitor - Changing the gamma to all red will allow you to see at least some green
External monitor needs adjustment to eliminate tint.
Blue, Red, And green
red blue and green
RGB - Red, Green, Blue
Try to get one more monitor just to check. If another monitor works with your computer, you have most likely problems with your video card (if you are not lucky it can be motherboard, or motherboard + video card).
3 - Red, blue and green.