Blubberykollis :
I do not have any issues with money.
I want to know which one is better for gaming.
I don't want a single gpu card. or a 2-way sli with single cards. just between these two.
Between the two, the 7990 has more graphics horsepower. That being said, the 690 not only runs much, much cooler, it also performs nearly as well and Nvidia's drivers seem to have fewer issues regarding SLI vs AMD's with crossfire and frame pacing, though that was theoretically fixed recently.
Basically, if you can manage to keep a 7990 cool, and you are driving a resolution higher than say 1440p, that'd be the way to go. But for most people, the 690 is more practical and even allows for a bit of overclocking to return the 680's to at or near stock clocks.