É um tópico um pouco antigo, mas para o pessoal com o mesmo problema, parece que agora a ATI começou a suportar gráficos legíveis comutáveis com seus últimos drivers 13.11 9.2 beta
Mais informações aqui: link
It has come to our attention that AMD has finally made changes to the way their official drivers install for switchable systems. I.E As far as we know, there is NO need for Modded 13.11 beta 9.2 AMD drivers that can be found on certain forums as the Official AMD release works out of the box for a certain percentage of switchable Laptops.
This means that as of 13.11 beta 9.2 AMD has incorporated switchable parameters into the kernel adding support for devices which they inherently did not want to support such as the 5xxx and 6xxxm series.
Link para download de drivers beta: link
Espero que isso ajude