conservative way - enable auto spd, it will enable 4-way interleaving.
more aggressive way - if your mb bios allows you to adjust detail memory timing, try set to "fast", "turbo" instead of "normal", "slow", or change something like 3T 6T 3T to 2T 5T 2T.
enable 4-way interleaving is faster.
from 64Mbit ram chip, 128Mbit, 256Mbit all are 4 banks inside.
the crucial 256MB uses 128Mbit chips, so only one dimm can have 4-way interleaving.