Single-drive Iometer performance
We haven't had time to conduct a full set of RAID testing yet, but I wanted to see the impact of NVIDIA's support for Native Command Queuing, so I ran a few tests on a single drive. The drive, in this case, was the same model as the system disk we used for all the rest of our tests, a Maxtor MaxLine III SATA drive with support for NCQ built right in.

Hmm. With NCQ enabled, the nForce4 is faster than all the other Athlon 64 chipsets in terms of operations per second and response times, but there are a few problems. The nForce4's performance with NCQ doesn't seem to scale right above a queue depth of 32, and at a queue depth of 256, Iometer consistently crashes. Also, the nForce4 can't touch the performance of the Intel 925X chipset, and CPU utilization on the nForce4 is markedly higher than everything else.

Let's see what happens with Iometer's database access pattern.

The database pattern shows us the same things. NCQ undeniably boosts performance on the nForce4, but there's a scaling problem with higher loads that reminds me of what we saw out of the nForce3 250Gb in our chipset RAID comparo. I'm unsure whether this is some sort of hardware limitation or simply a problem with NVIDIA's drivers.