How to change between integrated and discrete graphics in Windows 7?
Solution 1:
Switchable graphics is not an option unless the hardware and software are both designed with that function in mind, and in desktops they aren't usually.
Confirmation: https://community.amd.com/thread/211966
As you already learned, removing your discrete GPU allows the integrated graphics to function. Some BIOS allow you to manually switch without removing the discrete GPU, but many don't. However, even those that allow switching in a BIOS setting still require you to restart and get into the BIOS to make this change.
In laptops, switchable graphics are a special coordination of the discrete and integrated graphics systems and the mainboard they are connected to. Each of these components must be designed with this capability in mind, and this development was driven by the need for balancing performance and power.
This need isn't so great in desktop systems, where battery life is not a consideration at all, and where you'd have to get buy-in to the systems and protocols from myriad hardware vendors in order for the function to even begin to be reality.
So, the answer is most likely no. Selected GPU is a function of a hardware switch that in most BIOS is at least semi-automated: Discrete GPU installed? Disable integrated and run discrete.