How do I get my discrete card and my APU to work together?

So I recently addded an XFX Radeon HD 6670 card to my APU based system: I'm having an issue getting the card and the integrated graphics to work together. When I run benchmarks and FRAPS my fps are pretty high, but when I play the game there is a lot of studdering. If i turn off dual-graphics and only run the card, I don't have any issues. What can I do to get them to work together properly? 


> try uninstall drivers, run driversweeper , then re-install the latest cerified driver suite. 

>try enable/disable of the v-sync option.

Most likely will work with that suggestion.