been waiting for the first X58/Core i7 benchmarks to arrive and it seems like some have decided to jump the gun and in this case it's Reghardware that has a review of the Asus P6T Deluxe motherboard. However, it lacks some numbers that are related to CPU specific benchmarks as this is a motherboard review, not a CPU review.
There are some interesting results though, as Reghardware tested the motherboard with both triple and dual-channel memory setups and if the results are indeed accurate and we have no reason believing that they aren't, then triple-channel memory is going to disappoint.
On the other hand, it seems like the new memory interleaving of the Core i7 memory controller is vastly better than the ones used in older Intel chipsets. The board was tested using 3x1GB of memory at two different speeds, 2x1GB of memory and finally a 1GB and a 2GB module for a total of 3GB in dual-channel mode. In PCMark 05 the mixed modules managed to get within 19 points in the memory benchmark compared to the triple channel memory at the same speed.
However, the memory bandwidth doesn't get anywhere near the triple-channel configurations when you're only using two sticks of memory, but the latency is near enough the same. The results are similar in 3Mark 06, where the mixed modules are just 20 points the triple-channel setup.
You can find the review here