Depends on the game, nvidia is strongly focused on multiple GPU's.
Let's assume almost every game coming out on consoles are AMD optimized which seems to be the case with BF4 which has much lower frame latency and scaling than nvidia counter parts. Example would be the 7990 being 3-4 frames off the 780 SLI in BF4, that is incredible flawless scaling.
I assume the 290X which doesn't have crossfire bridges will also scale better according to AMD atleast. Who
knows, perhaps mantle will make scaling much better.
Most games today run better on SLI though, time will tell how much optimization developers can make with their games seeing as they are coding directly to AMD hardware. I assume that is how only they can make mantle possible.
Edited by Fniz92 - 10/12/13 at 7:52pm