SLI+third lesser card for physx?

So I've had the most amazing luck of a good resource for used hardware that managed to get me not only a working pair of EVGA geforce 7900GT KO superclocked cards(on two seperate occasions though), but recently a (at that time broken) quadro fX 1400, which as I read, is based on the geforce 6800 chip. I have a machine I'm building (pXE ES based 955 chip and a couple gigs of ddr2 from said place, though no board yet theres savings for a 780i new, as the 680i I got at this place was toast), and plan to use the two 7900s in SLI, but I want to know if, being that I plan to get a board with 3 PCI-E x16 slots, can I stick the quadro in as a physX card? Otherwise, It just sits on my shelf collecting dust waiting for me to touch up that cap and find a buyer for it...
~foxx~

The above is correct, the quadro uses a different driver and therefore it will not be recognised by the system. If you want a dedicated physx card then you can invest in a cheapish geforce card.