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SLI gaming: nForce4 SLI and nForce SLI X16 head to head
This next set of tests is intended to divine whether there's any real performance advantage in SLI mode for the nForce4 SLI X16 chipset's full 16 lanes of PCI Express connectivity to each of its graphics slots. Here we've tested the A8N32-SLI Deluxe against its direct predecessor based on the original nForce4 SLI core-logic chip, the A8N-SLI Deluxe. The old A8N-SLI has only eight lanes to each of its PCI-E X16 slots in SLI mode.

For these tests, the system configs were notably different from the rest of our benchmarks. The systems were configured as they were in our GeForce 7800 GTX 512 review, including the use of a pair of mega-speedy GeForce 7800 GTX 512 graphics cards and 2GB of RAM. The two motherboards were configured as close to identically as possible, including the all of the same memory timings settings exposed in Asus's BIOSes. If there's any extra headroom in the A8N32-SLI, these setups ought to be able to take advantage of it. Let's see what happens.

There's very little daylight between the two systems. The only really notable performance difference, if there is one, is probably between the two 3DMark05 scores at 2048x1536. There, the A8N32-SLI takes a slight lead. Still, it's nothing to write home about.

We've heard that one place where the extra PCI Express lanes can make a difference is with SLI antialiasing. This mode is apparently one of several special cases (along with applications that use render-to-texture techniques) where two graphics cards in SLI pass more data than usual between themselves via PCI Express. Do the additional PCI-E lanes help here?

Yep, a little. You might write home about this difference, but the folks at home would probably realize then that your life isn't very exciting.

All in all, the extra PCI Express lanes in the nForce4 SLI X16 chipset don't seem to help much, at least in the handful of apps we've tested here. Fortunately, they don't hurt, either.