For once, Intel doesn't have the usual plethora of documentation for this - the driver notes simply say:
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* 7. UNINSTALLING THE SOFTWARE
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NOTE: This procedure assumes the above installation process was successful. This uninstallation procedure is specific only to the version of the driver and installation files included in this package.
For Graphics:
1. Click on the "Start" button, then click on the "Control Panel" icon, and then click on "Uninstall a Program".
2. Select Intel(R) Graphics Media Accelerator Driver Software
3. Click the "Uninstall/Change" button and press Continue to uninstall the driver.
Your response about the BIOS is a little unclear to me, and your BIOS is, well, kind of bizarre - I've never seen anything quite like this. I'm assuming you have, on the "Advanced BIOS Features" page, set "Init Display First" to "PEG"; however, the actual 'toggle' for the on-board graphics chipset doesn't appear to have a flat-out 'disable' setting - most peculiar! The setting you want is "Enable If No Ext PEG", but don't ask me why there isn't just a 'turn the damn thing off!' setting? Nor does it appear you can actually disable the frame buffer memory allocation... My best suggestion is drop a note to GB here:
http://www.gigabyte.com.tw/Support/ServiceCenter.aspx
and see if these ditzy BIOS options are 'fixed' in a later BIOS rev for your board...
You don't seem to have posted whether this is a rev 1.x or 2.x MOBO - either way, I see no specific mention of any vidchip corrections in the BIOS lists,
but GB is
not particularly astute when it comes to thoroughness in their changelogs...