Asus P8-Z68-V Gen3 - Integrated graphics driver

I'm trying to use this motherboard, the Asus P8-Z68-V Gen3, with just the integrated graphics only (for now), but it will absolutely not let me install the drivers. It keeps saying it can't install because the system hardware doesn't support it. I've tried going into the BIOS and toggling Advanced / System Agent Configuration / GPU options (tried virtually every combination) but nothing works. All I can use is the Windows VGA driver.

Otherwise it works fine, but I want to be able to install the integrated Intel graphics until I can get a real graphics card in there.

Any ideas?

Thanks, Steve