I sold a computer with 17" monitor some time ago. After a few months I got a call that the monitor was now giving a vague image so I swappad it for another 2nd hand monitor, which gave up next day (after some knispering and banging inside, sounded loike a short-circuit) so I swapped it again, all free of charge:( by the way.
However I just got a call.....this monitor also collapsed. Since the last one was the monitor I had owned myself for two years, completely to my satisfaction, I start to wonder if something might be wrong: with the computer instead with the monitors? How can determine what's wrong there? By the way I'm not an electrician.