Asus has a Lucid Wizard that I used. Recommended steps follow below.
1) Set bios gfx to PCIE, connect monitor to discrete card ( in my case Radeon ) then install Radeon drivers.
All games work this way including OpenGL games with EITHER Radeon card. The system is fast and stable.
GpuCapsViewer reports OpenGL 4.2.
This is with no Intel Gfx drivers installed yet.
2) Enable dual gfx mode in bios, set gpu to iGPU ( Intel ), connect monitor to Intel, then install Intel drivers
- HD6870 GPUCapsViewer reports ( correctly )Intel HD 4000 OpenGL version 4.0
Intel OpenGL and DirectX work, just slower than Radeon. Both GPUs are correctly installed.
- HD7870, OpenGL does not work. GPUCapsViewer reports GDI Generic 1.1. DWM.exe crashes on bootup. Most DirectX titles work but not all.
3) Install Virtu MVP and reboot.
- Radeon 6870 - everything works including OpenGL, stable no crashes.
- Radeon 7870 - no point installing Virtu MVP. I can check the registry and see that Intel HD 4000 registry entries have amd dlls and drivers mixed in with Intel. This does NOT happen with the HD6870.
Heterogenous ( 2 different sets of drivers by different companies ) and Homogeneous ( 2 gpus , same drivers ) are supported as of Windows 7.
It is supposed to be possible to have GPUs from 2 different manufacturers and their drivers installed in Windows 7. If we couldn't, it would not be possible to use Virtu MVP. This is where the problem is. NOT with Virtu MVP. The problem exists BEFORE installing Virtu MVP.
I have used a fresh install of Windows 7 Ultimate 64 bit both with and without SP1 to test.
I have used different AMD and Intel drivers. I have tested with different versions of the motherboard bios. I have tried to install the drivers in the reverse recommended by Asus. I have reset the cmos and reloaded Optimized defaults in the bios. I have tried to disable one card while installing drivers for the other.
The problem is that the drivers are installing differently depending on the Radeon GPU installed. Catalyst 12.10 will work with HD6870 and Intel but not with HD7870 and Intel. I tried 13.1. I tried the beta drivers.
The question is, what is causing this difference?