The nForce4 and 975X are faster than their more mainstream counterparts in Sandra and Cachemem's memory bandwidth tests, but not always by much. Note that the P965's write performance is particularly good in Cachemem, likely because of Intel's new Fast Memory Access memory controller optimizations. The 570 SLI's write bandwidth is particularly poor by comparison.
Moving to latency, the nForce4 and 975X lead the way again, followed closely by the P965. The 570 SLI is way off the pace with a memory latency that's close to 50% higher than that of the P965.
Memory controllers don't always perform well when all four DIMM slots are populated, so we added a couple of additional memory modules to our test systems. On the nForce systems, we had to raise the DRAM command rate from 1T to 2T to get the boards to boot. Command rate control isn't available on the 975X or P965 boards we have, but they had no problem booting with four DIMMs without any fiddling.
The picture doesn't change much when all four DIMM slots are populated. However, the nForce 570 SLI's memory latency is greatly improved. 59.3 nanoseconds is much closer to what we'd expect from this chipset, despite the fact that we consistently observed much higher latencies with only two DIMMs installed.