Monitor turns on and off randomly

Hello,

I have a problem with my monitor that only recently happened. I have a Hanns-G JW199D monitor that keeps turning on and off randomly. it does it when I open too many tabs on firefox, sometimes when I watch a video, play games etc. There is no way I think I can predict when it might.

It works for a little bit (without problems) when I unplug the monitor for 15 min and then plug it back in. Also, I don't think its my graphics card Radeon 5960 as it works fine with my main display.

This problem just happened maybe a week and was working fine before. Could it just be that my monitor (which I bought around 2006) is nearing old age? Thank you.