http://www.xbitlabs.com/articles/video/display/geforce7900-quad-sli.html
Conclusion:
Basically, it crashes/freezes often, 32xSliAA is even slower than 16xAA while causing artifacts, and the performance does not live up to the expectations or the price.
Conclusion:
... Nvidia managed to declare its lead in consumer-oriented multi-GPU technologies by introducing its quad SLI ? a technique that allows four graphics processors to work together. While formally the company claim the lead in ?constructors? championship?, the current implementation of the quad SLI leaves much to be desired.
The quad SLI is here, the quad SLI is now shipping from a few companies. The reason why several big names, such as Alienware, are not yet shipping the quad SLI systems commercially amid formal launch is because this technology does not seem to be ready for commercial systems: users, who will utilize graphics cards to play games at extreme quality, will almost surely run into significant troubles with freezes, crashes, quality issues and so on. It transpires that Nvidia?s current quad SLI is not a product for buyers of luxury, as they desire stability and performance, not compatibility issues.
The quad SLI technology indisputably has potential: already now it demonstrates the highest scores in such games as F.E.AR., Far Cry with HDR enabled, scores best high-resolution numbers in Elder Scroll?s Oblivion, it wins Chronicles of Riddick tests, it produces amazing quality with 32xs SLI AA enabled, it does a plethora of great things. At the same time, it crashes in 3DMark05, Far Cry and numerous other games, produces artifacts when SLI AA is activated in Chronicles of Riddick and Serious Sam 2, which all degrades the value of this technology for the user right here and right now.
...
Basically, it crashes/freezes often, 32xSliAA is even slower than 16xAA while causing artifacts, and the performance does not live up to the expectations or the price.