Besides the obvious advantages described in our review, NVIDIA's SLI technology also has some unpleasant restrictions. One of them is you cannot join two GeForce 6800/6600 graphics cards into a SLI pair if the cards are not identical models made by the same manufacturer. It is as yet impossible to make a SLI configuration on GeForce 6600 GT or 6800 GT/Ultra out of graphics cards of different brands, even if their technical characteristics coincide.

This fact was proved in our tests, too. You may meet a serious compatibility problem if you?re willing to buy a single GeForce 6600 GT or 6800 GT/Ultra today and then upgrade this graphics subsystem with a second such card. In fact, there may be problems even if the second card is from the same manufacturer. The newer card may have a different BIOS, and not all people would dare experiment and reflash it.

NVIDIA, on its part, promises to correct this drawback in near future, thus giving the user more flexibility in applying the multi-GPU solution.

Another thing to be mentioned is that the GeForce 6800 Ultra PCI Express is still a relatively rare and expensive device, even after the recent release of the GeForce 7800 GTX. No wonder then that there have begun to appear special kits consisting of two graphics cards on NVIDIA GeForce 6600 GT GPUs that are guaranteed to be SLI-compatible. We received one such kit from Leadtek whose produce has been repeatedly tested and reviewed in our labs.

So today we?re going to talk about the WinFast PX6600 GT TDH SLI kit from Leadtek.