I've been using a Biostar GeForce 6100-M9 (M-ATX) with onboard graphics for 3 years. Everything was ok until I tried to add a Galaxy GeForce 9500 GT. Since then, the screen resolution is stuck at 640 x 480. Also, I can't change the refresh rate (stuck on 60 hertz) or color quality (stuck on 32 bit). I update the driver of the GeForce 9500 GT to version 188.8.131.5207 but nothing happens.
What is causing this? Can it be the onboard video interfering with my new card? Is it my motherboard?