I've been in contact with EA customer support for about a week trying to resolve this issue. In the end nothing they did could make my game run in fullscreen.
As far as I can see it looks like this problem is experienced by people with Nvidia 800M series on laptops running windows 8.1.
Is anyone able to run this game with a 800M series GPU?
Anyways, I asked if they could put this issue on their "known issues" list at http://help.ea.com/en/article/dragon-age-inquisition-known-issues/
They refused, saying it was a Nvidia problem. Which I find upsetting, especially on behaf of all the people who will buy this game and go into the same trap as we all have, and contact customer support and do the whole bloody list of default solutions to no avail whatsoever. I've seen people reporting this problem as far back as november 2014 and still there is no fix!
I petition to make this a known issue, its the least they can do.
Steps tried including, but not limited to:
Origin in admin mode.
DAI in admin mode.
In-game overlay disabled.
Reinstalled Nvidia driver to 350.12 (latest official)
Done Clean Boot
Deleted windows temp files.
Reset internet options in internet explorer.
Set DAI to always use High Performance Graphics processor.
alt+enter makes it go into a black fullscreen for 1 sec before returning to windowed.
I do not have Teamviewer.
Changed "Optimus flags for enabled applications" in the DAI profile in Nvidia Inspector to SHIM_MCCOMPAT_ENABLE from SHIM_MCCOMPAT_AUTO_SELECT. Then reverted the change since it didn't help.
Deleted DAI profiles from C:\Users\Runar\Documents\BioWare\Dragon Age Inquisition\Save
Moved .cab files from D:\Program Files (x86)\Origin Games\Dragon Age Inquisition\__Installer\directx\redist to a new folder, then ran DXSETUP.exe from the redist folder.
Booted windows in networked safe mode (made it run on the integrated Intel graphics only.)
Did you try isibon's suggestion at the top of this page?
"I was able to resolve the fullscreen issue in the NVidia control panel.
Go to "Adjust Desktop size and position"
Select the following options:
Full screen
Perform scaling on GPU
Override Scaling mode set by games and programs
The game will still start up windowed (despite being set in game options to fullscreen), but simply alt-tabbing into it will make it properly full screen."
As made clear earlier in this thread, that option is not available to laptop users.
I honestly don't believe that that's an NVIDIA or Intel issue, but more of a Frostbite 3 issue.
My laptop has a GeForce GTX 950 M and Windows 8.1.
I have a lot of games in my Steam library and none of those games have any problems with fullscreen, but I have 3 EA games which run on the Frostbite 3 engine and all 3 of them won't turn into fullscreen: DA:I, Battlefield 1 and Mass Effect Andromeda. (Edit: tested it with Battlefront II, same problem). Those are the ONLY games that have problems with fullscreen on my laptop, while all other games run perfectly fine in fullscreen. So I really don't believe that this is an NVIDIA or Intel issue alone, since it seems to only appear in combination with Frostbite 3. And since all other games I have which run on other engines work just fine, my guess is that it's totally a Frostbite 3 engine compatibility problem, which I won't believe comes only from NVIDIA and/or Intel, if not only from Frostbite 3.
Maybe they should rather check into this than just saying "it's an NVIDIA problem".
