Tearing will happen with any card you have, returning it won't help. Only return it if it is a bad overclocker
Most games you don't enable v-sync for will tear at some point, don't underclock the card because that won't help. Tearing is completely normal and will happen on every 680 you could possibly try.
You can either-
1) Leave v-sync off and put up with the tearing, but not suffer from mouse-lag and stuttering framerate when v-sync drops it by 1/2 when you can't maintain your monitor's refresh rate, or
2) Enable v-sync and eliminate tearing, but put up with the input-lag and framerate stutters
I personally leave v-sync off and use a framerate limiter set at my monitor's refresh rate (set at 120fps). I do have to put up with some tearing now and then, but I get no lag and the card doesn't work harder than it has to since the framerate doesn't needlessly go above my monitor's refresh rate