I have two super-clocked GTX 680 cards in my Hackintosh, they use the same chip (GK104) as the GTX 770. There is no SLI capability but OS X will "see" both graphics cards and CUDA applications like Octane (a rendering app) work great, and I assume OpenCL apps work too once the OpenCL drivers are installed.
When I boot into Windows I can use SLI to improve performance in games...it's not jaw-dropping...just a higher sustained frame-rate on my 2560x1440 display. Keep in mind that my cards are two years old now and faster cards didn't exist at the time. Today, one GTX 780 TI can provide close the same experience even on my 27" display, and the GTX 780 (no TI) is certainly no slouch. If you're sticking near HD resolution with a single display, then a GTX 770 is enough performance, even for games.