NETWORKING

- NVIDIA IEEE 802.3 Media Access Control (MAC)
Supports 10/100/1000Base-T
Ethernet/Fast Ethernet/Gigabit Ethernet*
- Supports HomePNA 2.0 PHYs
- Advanced Communication Riser (ACR) and Communications and Networking Riser (CNR) interface support

- High performance networking features
TCP segmentation offloads*
Jumbo frames*
Checksum offloads*

- NVIDIA StreamThru technology
Isochronous controller paired with HyperTransport results in fastest networking performance

* NVIDIA nForce3 250Gb only.

One of the major new features on the Nforce 3 250 is Gigabit ethernet. Being integrated directly into the MCP means that manufacturers will no longer have to rely on external solutions like the Realtek gigabit chip that seems to be quite popular amongst OEMs.

Gigabit ethernet translates into roughly 125 MB/s each direction. The PCI bus is limited to roughly 133 MB/s which means that if no other device was on the PCI bus besides Gigabit Ethernet, the PCI Bus will become totally saturated and will not be able to use Gigabit ethernet fully. This explains the need for PCI-X which provides higher bandwidth as well as Intel's desktop solution, CSA, which provides a specialized bus specifically for Gigabit Ethernet.

Nvidia has taken a similar yet different approach- instead of a dedicated bus, there is simply a high speed connection between the MCP and the processor. Nvidia demonstrated the prowess of their onboard ethernet controller when pitted up against an Intel PCI Gigabit Ethernet card. Two machines were connected via a cross connect cable. The server consisted of dual Xeon setup with an Alacritech TOE GbE NIC serving to a Nforce 3 based board with the Intel GbE card and the onboard Nforce 3 GbE NIC. Throughput was measured using IXIA's Chariot. With the Intel NIC, CPU usage was roughly 80% with throughput being around roughly 800 Mb/s. With the onboard Nforce 3 GbE, the processor usage dropped to around the 60% range while throughput skyrocketed to 1800 Mb/s. Keep in mind that the Alacritech card costs roughly 1200$ which puts into perspective the kind of performance that the Nforce3 GbE has.