TUMBLEWEED Changing GPU - From nVidia Nouveau To AMD AMDGPU?

Hi,

I have openSUSE Tumbleweed KDE 64Bit installed on a desktop.
The desktop currently has a very old nVidia GeForce GT 240 GPU.
I want to install a better AMD Radeon HD 7870 GPU.

What must I do after I physically install the AMD GPU?
On boot with nVidia Nouveau be automatically changed to AMD AMDGPU?

Let me know, thanks!

Jesse