I have to honestly say that I thought SLI would be the savior of these cards. While I was testing them I was extremely happy with the results and they looked extremely impressive, but once you put them into your graphs and begin to get a better perspective of how it compares to the other setups, you don't realize just how disappointing the results are. For the most part the GTX 280 in SLI and GX2 in Quad SLI perform the same, bar WIC AA/AF 2560 tests and Vantage.
Sure it's nice to see NVIDIA condense the power of two cores into one and four cores into two, but this doesn't come at a price drop. Unfortunately I didn't have my "power thingy" handy while at the IBuyPower Australia bunker, but what I thought was a quality power supply (1000W Zalman) wasn't able to handle the strain three cards placed on the system. Considering the water cooling pump uses only 24Watt, you can't even say that's the cause of it.
Like I said in the review of the ZOTAC GTX 280, the cards clearly have potential as far as PhysX and CUDA go, but it doesn't seem like they're ever going to be the performance beasts we thought they would be. After months of having Tri SLI and Quad SLI drivers out you would have think that NVIDIA would have improved on the technology, but adding a third card to your system and pulling another $600+ USD out of your wallet is going to be an extremely painful process.
As much as I would like to think NVIDIA have some magical driver around the corner that adds an extra 40% performance to the cards, the hard fact is it's highly unlikely as it would be ready now. It's been a while since NVIDIA has made a misstep in the graphics card world, but it looks like this could be one. It will be interesting to see what's going on with the GTX 280 in a few more weeks time; we can't see people embracing it like the 7800 and 8800 series of cards from yesteryear, though.