Ok I think I read this MB has 1 full 16x PCI-E slot and if the 2nd slot is populated it sets both slots to 8x.. I know this is a C-fire board but I have always had Nvidia cards not a bias just have them so whatever, Anyway I have a GTX260 216 in slot 1 and have a choice of 9600gt or 9800gtx+ for slot 2 ok so will dropping the GTX 260 to 8x be a bad thing and will I gain enough with the dedicated physx?? I know most people will say try it and see just wanting to know if anyone has tried a setup that reduces pci-e lanes to both cards and how that effects things if at all?
soooo ... you have a GTX 260 that can handle PhysX on its own, and you're thinking of adding a second card for PhysX? Not so sure about that one.
Over on the nvidia forums, there was a whole thread full of people testing out the exact same thing you're talking about. The conclusion seemed to be that in most cases, if you have a decent nvidia card already, offloading PhysX to a second card provides zero improvement in gameplay, with the only noticeable effect being to use more power and generate more heat:
One guy claimed a slight improvement, but on the other hand, a couple others claimed that offloading part of the work to an inferior card actually slowed things down.
With results like that, and considering that you'd be sacrificing bandwidth, it doesn't sound like this would be worth doing even if you got the second card for free, much less if you had to pay $100+ for it. I think the dedicated PhysX card option is mostly useful only if your main card is made by ATI.