tourist :
7750 GCN cards are not compatible with amd trinity dual graphics. If someone says they can ? be prepared to prove it with benchmarks and screen shots.
Just because the software is telling you it is working means nothing, amd started adding dual graphics support for richland in 13.1 drivers so i expect that is the reason people think it can work
I agree with you...for instance both my A10's HD 7660D iGPU and HD 6950 will show up under DEVICE MANAGER as working properly (although I can't run a monitor cable out the discrete card)... but the very fact that the results are near identical, when I ran 3D MARK first without a discrete card installed and then again with it installed. It shows that even though they both show up under DEVICE MANAGER and say they are functioning properly, they just wont work together.
Another thing I just learned last night.... is that there is an issue AMD has been aware of, since at least last summer.
When you install a second graphics card, you will no longer be able to access your BIOS upon start up. I watched a video review, where the narrator said AMD was working on this. Clearly they haven't fixed that either, since (at least in my case) by adding a discrete card I am not able to access BIOS either.
Now that is simply ridiculous to have to pull your card to do things in BIOS then always have to re install it again when you make changes. But anyway...the compatibility issue has a lot to be desired, Unfortunately, it seems you are stuck with a old tech 6670 or 6570 if you want a second GPU.