While the NVIDIA Forceware drivers claimed the video link connectors were not connected both sets of cards were connected to each other with a connector as shown below.
According to this Quad FX block diagram each pair of GeForce 7900 graphics cards are connected to a GeForce 570SLI chipset, which means each chipset would have a pair of cards in SLI connected to it. Sadly when the system restarted SLI was no longer enabled. Just to be sure it wasn’t enabled we ran some benchmarks after SLI was enabled and the results of the system are sown below.
Running a pair of GeForce 7900 GTX and 7900 GS graphics cards scored 6794 3DMarks in 3DMark06, which isn’t that impressive considering the pair of XFX GeForce 7900 GTX cards in SLI scored this:
It’s obvious that Quad SLI didn’t enable, but it was worth a shot as you will never know unless you try. From the performance numbers I saw it seems that only one GeForce 7900GTX is cranking out the graphics, so SLI did not enable on any of the sets of graphics cards. It was still pretty cool having four graphics cards installed and running in Windows XP Pro.
Running four graphics cards went smoothly and although I don’t have eight independent displays to test out the cards to the max they did run on my four displays just fine. For now if you want to run Quad SLI you’ll have to run a pair of GeForce 7950GX2 graphics cards and not four individual cards even though four x16 PCI Express slots are available. If you are looking for a system that can run four video cards and eight independent displays it looks like AMD’s Quad FX platform fits the bill.