Could you please specify your laptop model?
I've a Toshiba i3 3110M and 7670M but couldn't find a fix to using both GPUs. I understand both can't be used together, that's for sure in my laptop's hardware but i expect it to run Intel HD 4000M for low performance tasks and 7670M for high performance tasks. It's similar to NVidia Optimus. AMD has something called Enduro but i'm figuring out how to do it.
If someone has got an answer please post here.