I have a dual-Opteron 250 (2.4GHz) set in Tyan Thunder 2885 K8W with AMIBIOS version 2.05. In the BIOS setting (Chipset->memory config -> Bank Interleaving), I am asked to choose between AUTO & DISABLED. No choice is offered for Node Interleaving.
The only guidence for the choice is that interleaving allows memory access to spread out over banks on the same node or across nodes decreasing memory access contentions. Nothing is mentioned about what happens when Interveaving is disabled. Furthermore, if I choose AUTO, then I do not know when the memory is spread out over banks on the same node or across nodes.
Node interleaving means you address all your memory as one big block with pages being alternated between the nodes. This means half your memory calls will be across the hypertransport bus, slowing them down. You dont really want to do this.
Stick with bank-interleave on auto and node-interleave disabled for best memory performance. (Bank interleave will be used if you have enough compatible DIMM on a cpu to make it work)
To compare the performance, download the source for the Stream memory benchmarking code and let it rip.