How to Set your Memory Timing in BIOS
The BIOS on your motherboard offer numerous settings to optimize your memory.
These settings modify RAM functions that, while basic in nature, are often given
widely different names. There are five basic settings that if set correctly can
help optimize your memory. We'll briefly explain the options. We've also included
examples of what the settings might be called in different BIOS versions.
NOTE: Not all BIOS menus offer all these settings.
- tCL - CAS Latency (also labeled as CAS Latency Time, CAS Timing Delay)
The number of clock cycles that pass from the column being addressed to the
data arriving in the output register. The memory manufacturer lists the best
possible setting as the CL rating.
- tRCD - RAS to CAS Delay (also labeled as Active to CMD) Number of
clock cycles that pass between the row address being determined and the column
address being sent out. Setting this value to two clock cycles can enhance
performance by up to four percent.
- tRP - RAS Precharge Time (also labeled as RAS Precharge, Precharge
to active) Number of clock cycles needed to precharge the circuits so that the
row address can be determined.
- tRAS - Row Active Time (also labeled as Active to Precharge Delay,
Row Active Delay, Row Precharge Delay) Delay that results when two different
rows in a memory chip are addressed one after another.
- CMD - Command Rate (also labeled as CMD Rate) Number of clock cycles
needed to address the memory module and the memory chip with the desired data
zone. If your memory banks are full to capacity, you will have to raise this
rate to two, resulting in a considerable drop in performance.
Memory timings are usually in the following order:
tCL - tRCD - tRP - tRAS - CMD
For example, our PDC1G3200LLK has a timing of 2-3-2-5-t1. This translates to the following:
tCL = 2 tRCD = 3 tRP = 2 tRAS = 5 CMD = 1
We've also included examples of what the settings might be called in different BIOS versions.
Please note that not all BIOS menus offer all the settings It is recommended that
customers using our Patriot Extreme Performance or Dual Channel memory set their
BIOS to the settings specified for their memory.