what power supply do you have? A 1200?, i hear Galaxy is making a single slot GTX 680....lol i know you don't need not 680!.
Well here is the thing i am sure the Desktop GT 640 or what ever it is. wil be out soon. if you need one pronto then a GT 430 or 520 will do the trick!
Yeah it's Corsair AX1200. one slot 680 with air cooling????? Sounds... interesting:)
I've never seen one slot 5xx series VGAs, except water cooling one, but that's not an option for me, why do you think they will make it in 6xx series?