Disable onboard graphics in BIOS, through Device Manager, or a switch that the laptop probably has.
Read carefully the manual, download it if you have to, or just google it.
The problem seems to be a driver compatibility issue between the two adapters.
They each presumably need a different driver.
Use only the dedicated (HD 5650), and manually install the latest supported drivers for that, from the official AMD site.
Do not use the auto-detect tool.
gigabyte X58A-UD3R rev.2, core i7 975 3.9ghz (stock voltage), windows 8.1 64-bit, corsair 12gb DDR3 1600mhz 7-7-7-20 RAM, sapphire HD 6990 (stock clocks), coolermaster ultimate 900w PSU.
amd catalyst 14.6 RC2 june23