How to organize the work of discrete and built-in video cards?

Question

Video cards

Is it possible to organize the joint work of two video cards: there is a PC with an AMD APU A4-3300 processor with an integrated Radeon HD 6xxx video card, there is also a separate video card (from an old computer) Radeon HD 5570.
I checked the compatibility of the motherboard with a discrete video card, they seem to be compatible, but by connecting to the last board, the monitor did not function ... unlike the video card and the computer as a whole. Those. Everything works, but it doesn't work at the same time. I also connected the monitor to the "native" input - this combination is also unsuccessful.
Please help me figure out if this makes any sense at all.
Everywhere there is information about crossfire, but here they don’t seem to work at all.
Thanks in advance!

Answer 1

If I'm not mistaken, this is called "hybrid graphics" By google in this direction. I don't know anymore.

Answer 2

Your configuration does not support the simultaneous operation of integrated graphics and a discrete adapter. It's easier to take the cheapest adapter from the latest series, they support up to four monitors at the same time