Best GFX card for both Auto CAD and gaming?

Topic title says it all. I don't know much about CAD nor the best GFX card that can do CAD and gaming at the same time. What would be a good solution? Because I'm helping a former co worker build a PC for his architect work as well as playing games like Arma III and other war base games.

His budget is $1000 and he's getting an i7 and 8 GB of RAM.

i7/Xeon/FX8 series along with 16Gb RAM is needed, now if you want good GPU for editing and gaming at the same time I recommend the Titan.

I'd go for the Titan as well.

Maybe I didn't make it clear, he's budgetting a PC build for $1000 USD, so let us subtract the i7 and RAM off for now, because a Titan won't fit in his budget.

And you have gone by the 1000$ mark by miles.

Wouldn't he benefit from I7 extreme?

That really depends on his prioreties, also on which settings does he wishes to play ARMA 3

He'll be gaming on his TV, I plan on giving him both Steam OS and Windows 8.1 Pro so the best he can play ARMA is at high settings

You dont need to get a Titan. Just get a GTX 780 or 780ti. Or even a 770. Auto cad's performance is influenced by motherboard chipset and harddrive speed too. You will not see any real difference with intels six core cpu's or Xeon based cpu's.

Just pick up a i7 4770k (for overclocking) pick up an ASUS based Z87,motherboard and one of those GTX 770 or better cards and make sure to get an SSD like SAmsung EVO's. and he will be set.