Well "quality" maxes at 60 fps but that itself is subjective. Most people though want to to see 45-60 fps in the games they play. Any less is noticeably choppy. So if you have multiple cards that cause you to get insane high fps you are not getting any real benefit. Now multiple cards are good for super high resolutions and or multiple monitor setups. I would say that a 680 is more than enough to play any game at good fps today, With a $1000 budget to include a monitor SLI is not out of the option but not really needed for the resolutions you will most likely be playing at unless you want to sli two lower in cards which can offer you a little more performance for a little less money but with sacrifices such as power consumption, heat, noise, and space. If you are looking to build you honestly need to think about what you want in the end. You need to think about your budget, cpu, mobo, gpu, case, power supply, monitor, etc. They all have an effect on each other and should be bought to compliment each other.