680 SLI is a tad OTT for a single 3D 1080P screen, a single one would suffice. Now that you've got it you may as well keep it though
I wouldn't dare send it back (shipped, don't have them yet) unless defective. As I've said above I think OCUK would ban me after 2 recent cards I've sent back . I'll just have to add 2 screens when I've got the money, still to buy the first one though and other things (PSU/Kboard/Mouse/ExtraGlasses). I hope the second card will do me justice in some situations in 3D as I'd hate to waste it.
Do you still have the 7970s Lightning?. If so, how are you finding them?.