Memory tests and HEXUS.PiFast
Memory bandwidth is practically identical between the DDR2- and DDR3-equipped motherboards. Latency is a little better with 'D2 on the nForce 680i SLi board but not quite as good on the Foxconn X38, although it was a pre-production board.
We can call stock performance a draw on Intel mainboards. The nForce 680i SLI struggles just a touch, although you could never visually determine the difference in our number-crunching test.