flickering lines on video playback

hi, this is my first post and hope someone can help me!
I built my first computer a few months ago and installed a radeon x700pro. it worked fine at first but then i started getting flickering lines down the screen when playing video files or dvd on a media player. I figured it was a fault so sent it back and got an x1650 pro instead. I just installed it today and have the same problem. are there any suggestions what this could be and how i could fix it?
Thanks in advance

 

A specific media player or any media player?

I would first try to install the latest video drivers and go from there.

good luck

 

yeah i have tried every media player under the sun. the on board video card which i was using before installing the new one played everything fine. i have uninstalled drivers for said on board card and installed the drivers for the new one, is this what your refering to? or do you mean like codecs?