I just recently bought my second Nvidia GTX 670 4gig GPU. When i go to the Nvidia control panel and the "Configure SLI, Surround, Physx tab...what settings should i choose for best power and performance? currently under SLI config. I have it set to Maximize 3d performance and Physx settings I have it set to my second card with "Dedicate Physx" box unchecked
That sounds like the default setting... Auto Select (Recommended) which is always good. There's no real reason to dedicate a card to physx. Physx doesn't take that big a toll on a card and not all games make use of physx.
More important is the Manage 3D Settings - Global Settings in the Global Settings tab. These are the recommended settings according to Koroush Ghazi who used to write game guides for GeForce.com. http://www.tweakguides.com/NVFORCE_6.html