Notice N5406 - System bandwidth appears to be memory limited. Generally this means that memory bandwidth is < 50% FSB bandwidth, thus CPU is starved. This generally indicates a mismatch between memory and system. Note that this does not indicate that memory timings are wrong, but the memory itself is slow.
Fix: Use higher performance memory (e.g. DDR/2/3 or even RDRAM) or use any additional memory channels (if present) to increase memory bandwidth performance.
For more information, please see the (FAQ).