I finally got it working, after so many tries and hours (days) on it.
The new ATI 14.2 beta is out, and it might helped.
Here are some notes:
Card: XFX 250 R7 GDDR5 1GB
MB: ASRock FM2A75M Pro4+, BIOS: v1.90.
V2.0 does not work--it will not show the "Dual Graphics/Surround View" options. I contacted ASRock and I'm disappointed they think it's not thier fault.
BIOS-> North Bridge Configurations:
IOMMU: Disable ;IDK if this matters or not, but I will test it a bit later.
Primary Graphics Adapter: PCI Express or Onboard ;Does not affect the dual-graphics being available or not in Windows.
Share Memory: 1GB ;This depends on the amount of system memory you have, and may not affect the dual-graphics being available or not in Windows. My assumption: If the primary is the dedicated (250 R7 in my case), this option might not even matter. In crossfire, only the primary card would use its memory, so if you have two 2GB cards in CF, the memory available would only be 2GB--not 4GB combined.
Onboard HDMI HD Audio: enable or disable
Dual Graphics/Surround View: Enable. ;Auto will cause problems, and this is why; Dual-graphics in Windows will still show, but with this on Auto, the dual-graphics options being enable or disable will always reset--Just leave it on enable.
DVI Function: as Dual Link DVI or as HDMI ; does not affect the dual-graphics being available or not in Windows.
My RAM: DDR3 1333MHz.
re"> This might been the main problem, as others here have mentioned. At 1333MHz, and even OCed to 1600MHz, the dual-graphics option in CCC will NOT show-up. Could be the board, or how AMD limits dual-graphics with lower-speed memory sticks. But once I OC'ed both sticks to 1866MHz, the dual-graphics option in CCC does show-up.
re"> Note: You can see if both cards are working ad installed properly within CCC under Information, then Hardware.
With dual-graphics enabled, and with the onboard as primary, Assassin Creed Black Flag was able run between low-to-normal details smoothly.
With dual-graphics enable, and with the 250 R7 (GDDR5) as primary, the game is much MORE smoother than the onboard as primary, even with details at high and FXAA on. ASRock manual says to connect the HDMI to the onboard, but ATI recommends to connect it to the more powerful card. In this case, the GDDR5 used in the 250 R7 runs better, than the higher stream cores in the A10-7850K. So as many have suggested also, it is important to pair this APU with very fast memories--since they use shared memory.
Trouble-shooting (for those who might have similar problems)
I recommend using DDU (Display Driver Uninstaller) to completely uninstal any ATI driver properly.
re"> My setup has a problem with the ATI driver installation process. If I were to install the driver package with both the 250 and onboard physically installed or enabled (in Windows), the installation would freeze or does a infinite looping thing where the progress bar would just move, but never done--so my installation would never complete. To fix this: (1) I can either install the ATI driver completely with the 250 NOT pysically installed first, OR (2) just disable the onboard fully in the BIOS first. Then, (1) afterwards physically install the 250 OR (2) re-enable the onboard afterwards.
re"> - If you do still problems with both the 250 and onboard within Windows. For example, either the 250 or onboard being disabled in Windows Device Manager, then try this: Ctrl+Alt+Del, run Task Manager, and end all ATI processes like CCC, CCC monitor, CCC fuel something, etc., then enable (in Windows Device Manager) both the 250 and the onboard.
If you do still have problems, I still recommend using DDU (google it, probably on Guru3D site for download), and try the ending all ATI processes in Task Manager. Good luck, and I hope this additional info along with others here helps.