The Southbridge Battle: nforce 6 MCP vs. ICH7 vs. ICH8

Nvidia Media Communications Processor (MCP, nForce 6 Series)

Nvidia's Media Communications Processor (MCP) for nforce 6 offers six Serial ATA/300 ports with NCQ and a total of 10 USB 2.0 ports. The fact that the nforce 680i SLI chipset offers the best feature set of all the core logic products for Core 2 Duo does not necessarily mean that it does everything best as well. Let see:

For some reason, RAID 0 performance with four hard drives was disappointing. While the two Intel Southbridges reached 300 MB/s read and 280 MB/s write transfer rates, the Nvidia solution was stuck at 115 MB/s max. At the same time, Nvidia's MCP clearly is the better solution for RAID 0+1. Although it cannot outperform the 134 MB/s transfer rate the ICH7 and ICH8 offer for read speeds, Intel's device write transfer rate drops to 78 MB/s (roughly the equivalent of a single hard drive), its MCP transfer rate is a faster 106 MB/s. At RAID 0+1, Nvidia offers the best overall performance.

The RAID 5 situation is different. Intel's ICH7 and ICH8 are capable of providing an amazing 225 MB/s read performance with the four hard drives in RAID 5, while the nforce 6 MCP is limited to the 115 MB/s we already saw in RAID 0. RAID 5 write performance is even worse at only 28 MB/s. Things get interesting with a degraded RAID 5, as the Nvidia solution maintains its performance level and outperforms the Intel products by at least twofold. The slow write performance is a result of missing write back caching, which we don't criticize for a RAID 5 setup, as data safety should be more important than performance here. Yet we cannot explain the maximum bandwidth of 115 MB/s.

In terms of I/O performance, Nvidia's chipset performance falls in between ICH7 and ICH8, which also applies to USB 2.0 performance. With a single hard drive, Nvidia scores second best. Using two drives on the same USB 2.0 root controller, the Nvidia MCP maintains 20.3 MB/s, while the Intel ichs drop to 18.8 MB/s. Attaching two drives to different controllers place the MCH's performance between ICH7 and ICH8 again.