Code:
Section "Device"
Identifier "Videocard0"
Driver "nvidia"
Option "SLi" "SFR"
Option "RenderAccel" "True"
Option "NoFlip" "True"
Option "AllowGLXWithComposite" "True"
Option "Triplebuffer" "True"
EndSection
Just set the option "Tripplebuffer" to "True" in your xorg.conf, dunno if this helps the tearing graphics though, V-Sync is used to solve that usually.