Nvidia FAQ states:Is there a special driver from Nvidia for SLI mode, like OP states he using in post #10?
Ref:Which driver should I use?
NVIDIA® ForceWare® Unified Driver Architecture (UDA) supports SLI technology. Simply download the latest GeForce or Quadro graphics driver from the driver download page located here.
NVIDIA continually adds new SLI applications profiles to upcoming drivers. For the most up-to-date SLI application support, always use the latest drivers.