Memory tests and PiFast
When using DDR3-1066, the X38A and P5K3 Deluxe score slightly above the DDR2-equipped boards in bandwidth tests, as well as beating their Intel DDR2-800 counterparts in terms of latency.
The nForce 680i SLI actually offers the lowest latency overall, yet when it comes to PiFast it's the slowest board by roughly one second.