You don't have a separate graphics card.
The integrated graphics that comes in the Phenom 9550 is not enough to play games.
Also, 9550 is barely a minimum for many games.
It may work on The Witcher 3 but you will need a good graphics card.
Something like AMD Radeon R9 270X is just around your price range and will run games at low to medium graphics.
Newer games will require better processor.
Ideally, you would need completely new pc.