The Definitive BIOS Optimization Guide
http://www.techarp.com/freebog.aspx
If you do not find the exact setting listed from your Bios choices please go to the link above and look there.
SDRAM Bank Interleave
Common Options : 2-Bank, 4-Bank, Disabled
Quick Review
This BIOS feature enables you to set the interleave mode of the SDRAM interface.
Interleaving allows banks of SDRAM to alternate their refresh and access cycles. One bank will undergo its refresh cycle while another is being accessed. This improves memory performance by masking the refresh cycles of each memory bank. A close examination will reveal that since the refresh cycles of all the memory banks are staggered, this produces a kind of pipelining effect.
However, bank interleaving only works if the addresses requested consecutively are not in the same bank. If they are in the same memory bank, then the data transactions behave as if the banks were not interleaved. The processor will have to wait until the first data transaction clears and that memory bank refreshes before it can send another address to that bank.
Each SDRAM module is internally divided into either two or four banks of memory. Double-banked SDRAM modules generally use 16Mbit SDRAM chips and are usually 32MB or smaller in size. Quad-banked SDRAM modules, on the other hand, usually use higher density (64Mbit-256Mbit) SDRAM chips. All SDRAM modules of at least 64MB in size are quad-banked in nature.
If you are using a single double-banked SDRAM module, set this feature to 2-Bank. This is the only option available for the single double-banked SDRAM module.
If you are using at least two double-banked SDRAM modules, you can use the 4-Bank option as well as the 2-Bank option. Of course, it is recommended that you select 4-Bank for better interleaving performance.
If you are using quad-banked SDRAM modules, you can use either interleave options. Of course, it is recommended that you select 4-Bank for better interleaving performance.
Because a 4-bank interleave always allows for better interleaving performance, it is highly recommended that you select the 4-Bank option if your system supports it. Use the 2-Bank option only if you are using a single double-banked SDRAM module.
Please note that Award (now part of Phoenix Technologies) recommends that SDRAM bank interleaving be disabled if 16Mbit SDRAM modules are used. This is because early 16Mbit SDRAM modules have stability problems with bank interleaving. The good news is all current SDRAM modules support bank interleaving.
OR
Force 4-Way Interleave
Common Options : Enabled, Disabled
Quick Review
This BIOS feature allows you to force the memory controller to use the 4-bank SDRAM interleave mode which provides better performance than the 2-bank interleave mode. However, you must have at least 4 banks of memory in the system for this feature to work properly.
Normally, SDRAM modules that use 16Mbit memory chips (usually 32MB or smaller in size) have only two memory banks. So, if you are using such a small capacity DIMM, you should disable Force 4-Way Interleave. But if you use two or more of such DIMMs, you can still enable Force-4-Way Interleave.
SDRAM modules that use 64Mbit or larger memory chips are four-banked in nature. These modules are at least 64MB in size. If you are using such four-banked modules, it no longer matters if you are using just one module or several of them. You can enable Force 4-Way Interleave without fear.
Therefore, it is recommended that you enable this BIOS feature if you are using 64MB or larger memory modules or at least two 32MB or smaller memory modules. Otherwise, it is best to disable this BIOS feature.
For more information on memory bank interleaving, you should check out the details of the SDRAM Bank Interleave BIOS feature.
OR
DRAM Interleave Time
Common Options : 0ms, 0.5ms
Quick Review
This BIOS feature determines the amount of additional delay between successive bank accesses when the SDRAM Bank Interleave feature has been enabled. Naturally, the shorter the delay, the faster the memory module can switch between banks and consequently perform better.
Therefore, it is recommended that you set the DRAM Interleave Time as low as possible for better memory performance. In this case, it would be 0ms which introduces no additional delay between bank accesses. Increase the DRAM Interleave Time to 0.5ms only if you experience instability with the 0ms setting
Command Rate!
Common Options : 1T, 2T
Quick Review
This BIOS feature allows you to select the delay between the assertion of the Chip Select signal till the time the memory controller starts sending commands to the memory bank. The lower the value, the sooner the memory controller can send commands out to the activated memory bank.
If the SDRAM command delay is too long, it can reduce performance by unnecessarily preventing the memory controller from issuing the commands sooner.
However, if the SDRAM command delay is too short, the memory controller may not be able to translate the addresses in time and the "bad commands" that result will cause data loss and corruption.
It is recommended that you try the 1T command delay for better memory performance. But if you face stability issues, increase the command delay to 2T.
OR
SDRAM 1T Command
Common Options : Enabled, Disabled, Auto
Quick Review
This BIOS feature allows you to select the delay between the assertion of the Chip Select signal till the time the memory controller starts sending commands to the memory bank. The lower the value, the sooner the memory controller can send commands out to the activated memory bank.
When this feature is enabled, the memory controller will only insert a command delay of one clock cycle or 1T.
When this feature is disabled, the memory controller will insert a command delay of two clock cycles or 2T.
The Auto option allows the memory controller to use the memory module's SPD value for command delay.
If the SDRAM command delay is too long, it can reduce performance by unnecessarily preventing the memory controller from issuing the commands sooner.
However, if the SDRAM command delay is too short, the memory controller may not be able to translate the addresses in time and the "bad commands" that result will cause data loss and corruption.
It is recommended that you try enabling SDRAM 1T Command for better memory performance. But if you face stability issues, disable this BIOS feature.
