Two Different nVidia GPU, One as Graphics, One as Physics - Possible? | Super User
Waylan Choy stashed this in Computing
In multi-GPU mode, one GPU handles all graphics duties, while the second card is solely responsible for tackling all physics commands. Under this mode end users can mix and match different cards. For instance, someone who purchased a GeForce 8800 GT last year can run this card for physics, and then pick up a brand new GeForce GTX 280 to run as the primary graphics card for gaming. An SLI motherboard isn’t required for this mode either, both SLI and non-SLI motherboards are supported."
for reference, for anyone with a tower...mostly just a reminder for myself. this link is the better one discussing the config ("dissimilar" is a good search term, as opposed to simply "different").