Ethernet performance
We evaluated Ethernet performance using the NTttcp tool from Microsoft's Windows DDK. The docs say this program "provides the customer with a multi-threaded, asynchronous performance benchmark for measuring achievable data transfer rate."

We used the following command line options on the server machine:

ntttcps -m 4,0,192.168.1.25 -a

..and the same basic thing on each of our test systems acting as clients:

ntttcpr -m 4,0,192.168.1.25 -a

Our server was a Windows XP Pro system based on Chaintech's Zenith 9CJS motherboard with a Pentium 4 2.4GHz (800MHz front-side bus, Hyper-Threading enabled) and CSA-attached Gigabit Ethernet. A crossover CAT6 cable was used to connect the server to each system.

The nForce4 boards were tested with the NVIDIA Firewall and Jumbo Frames disabled.

Gigabit Ethernet performance is mixed for the RDX200. On one hand, the board's PCI Express-connected Marvell 88E803 boasts impressive throughput. On the other, it exhibits higher CPU utilization than other GigE implementations, including the nForce4's integrated Gigabit Ethernet. The RDX200's PCI-based Marvell 88E8001 is a total disaster; throughput is less than half that of the PCI Express GigE implementations, and CPU utilization is nearly 50%. Again, we're seeing extremely poor performance from a PCI-based peripheral connected to the SB450 south bridge.

We should note that it took DFI's latest BIOS, version RDXDB23, to squeeze acceptable PCI-E Gigabit Ethernet performance out of the RDX200. Older BIOS revisions exhibited higher CPU utilization and much slower throughput.