Tech ARP has just added the Read Preamble Time to the BIOS Optimization Guide.
We have just posted the Read Preamble Time BIOS feature today. This brings the BIOS Optimization Guide to more than 380 BIOS features.
"This is an AMD Athlon 64 / Opteron processor-specific BIOS feature. It controls the amount of read preamble, a period during which the processor's built-in memory controller intentionally delay..."