After starting game my monitor goes black

So after few days me and my friend we where playing dead island. Then suddenly my screen went black but still I can hear sound of the game only. Then that smell came from my desktop like something was burned I don't know what but it seems from power supply because I tested again I turned back on game and waited for few minutes and the smell was coming like from power supply what I have tested now is counter strike 1.6 battlefield bad company 2 it works But like world of warcraft or dead island garrys mod and probably other games don't work
My pc spec are
*OS:Windows Vista Ultimate
*CPU:Intel Core Quad Q6600 2.40Ghz
*GPU:GTX260
*RAM:4GB
*Hard drive:1TB
*Power Suppply:700W
I just don't know what do to

Some people saying that I need to replace new power supply and later on new graphic card

What is the make of your power supply? A bad power supply will cause all kinds of issues and if you are not careful will damage other hardware components. Remove said power supply.

This pc it was good and it has been working good from 2009 my power supply OCZ MODXSTREAM-PRO