PhysiX cards aren't worthwhile to put money into them, there aren't any end products which utilize it...So, get either two or three 9800GTX's or two 9800GX2's, if you're insane enough to spend that much money on that many...Note that only two 9800GX2's can be put in SLi, there aren't any drivers which would allow you the use of three 9800GX2's...On top of the hardware and space limitations, you just simply can't fit three 9800GX2's on a ATX motherboard...
Three-Way SLi is (So far) available only to these NVIDIA GPUs:
GeForce GTX 280
Geforce GTX 260
And these NVIDIA motherboard chipsets:
nForce 790i Ultra for Intel
nForce 790i for Intel
nForce 780i for Intel
nForce 780a for AMD
nForce 680i for Intel
If you have that much money (AKA more money then sense ) however, you'd be better off waiting to buy the GeForce 280's and 290's...Or getting three 260's in Three-Way SLi...But GeForce 280's and 260's are overpriced and are underpowered when if you check its performance to price ratio...So they aren't really worthwhile until they have a significant price drop...
The best deal right now, for the money, is getting two or three 9800GTX's...Simple as that...
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