Well, you can cool a cpu and gpu on either rad, but it all depends on the speed of fans you want to run. You can turn the fans down on either rad, but where do you want the most performance? low rpm and silent or higher rpm and "loud". The Sr-1 is the best performing rad with <850 rpm fans and the gtx is best for 1500+ rpm fans. The SR1 beats the gtx under ~ 1500 rpm and the gtx slaughters the sr1 above that rpm. 2x either of those rads will cool that setup no problem. You can get away with 2x sr1 240s with ~1200 rpm fans and still have decent temps. You'd even be able to turn them down when not gaming.
edit: we don't know the TDP of the kepler gpus yet, but I'm assuming it's no more than a gf100 (gtx 480). With 2x gtx 240s with 2000+ rpm fans you will have great temps. Other than that you'll be looking at mediocre ones (around a 10c water/air delta)
This will help you pick a radiator. It shows the relative performance of each rad dependent upon the speed of fan being used. Just pick the one with the lowest bar with the fan rpm you plan to use. Anything under ~1200 rpm is usually pretty quiet
Edited by fat_italian_stallion - 5/15/11 at 8:21pm