I've selected 'GFX0-GPP-IGFX-PCI' setting for 'Primary Video Controller' and Disabled Surround View.
There is no option to 'Disable' the Onboard Video
And I've plugged in both the 6-pin PCI-E Power connectors to the card.
(In fact, I can play Crysis at High Settings at 1280x960, but that's a 4:3 resolution! All these problems happen only with 16:10 resolutions)