As an owner of many NVIDIA cards over the decade and also as a proud owner of one GTX 680 (got lucky and was able to get one at NewEgg within a couple of days of its availability), I can honestly state that in the case of the GTX 680, NVIDIA got the reference design just about perfect. I haven't seen a single after-market design that improves upon the reference's balance of quiet & efficient cooling (exhausting the air outside, rather than inside the case), and the reference design called for high-quality PCB & capacitors too. The only real "improvements" come from liquid-cooled versions.
PLEASE MAKE SURE YOU HAVE UPDATED to the latest 310.90 drivers! THE PRIOR 310.xx drivers actually have a critical security vulnerability which, although difficult (but not impossible) to exploit remotely, could give a malicious attacker super-user privs even on a limited account (which is always the problem with low-level driver security flaws).
Download the latest drivers here: http://www.geforce.com/drivers
Read up on the security vulnerability here: http://news.ycombinator.com/item?id=4966380