Try running the memory at 1866Mhz, 2133Mhz or 2400Mhz and see if that enables Dual Graphics. The toggle will appear as AMD CrossFire under Radeon Settings > Gaming > Global Settings.
Thanks for your response. I ran the memory at 2400 MHz using AMP, but still could not get Dual Graphics to work. Have not tried the other frequencies yet.
I have another system with A10-7860K, MSI A88X and XFX R7 250 2GB DDR3. I was able to enable Dual Graphics on that one. So, to troubleshoot,
1. I installed the R7 240 in the A10 system. No Dual Graphics.
2. I installed the R7 250 in the A8 system. Dual Graphics worked!
This seems to suggest the R7 240 is the culprit here. But what could possibly go wrong with this card? I have verified using GPU-Z that it has a Oland GPU.
The specific model number is MSI R7 240 2GD3 LP purchased from Newegg.
The GPU-Z and Radeon Settings screenshots are attached below.
For dual graphics to work both GPUs have to be the same in almost every way. The same applies to the apu/gpu marriage. Both are of the R7 family, but clock speeds and DirX versions do not match. I would suspect that the DirX conflict to be the culprit.