It pulls 433W with 100% GPU stress, not CPU + GPU stress. It even says on the bottom of the page:
BTW we stress the GPUs here,. not the processor, so you need to add another 100~150W for overall power consumption.
For safety reasons and some expandability, he should go with at least 650W, but I guess it doesn't matter now since he bought a 850W, though I wouldn't say it's overkill since that thing will probably last him quite a few builds down the road.
Back on topic, if I had 460 SLI I'd just game on a single 1920x1080 screen. Keep in mind that even if you go with 3x 1440x900, you'll basically be putting a similar workload on those cards as if you were running a single 2560x1600 monitor.