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SDRAM Idle Limit

Common Options : Disabled, 0 Cycle, 8 Cycles, 12 Cycles, 16 Cycles, 24 Cycles, 32 Cycles, 48 Cycles

Quick Review

This BIOS feature sets the number of idle cycles that is allowed before the memory controller forces open pages to close and precharge. It is based on the concept of temporal locality.

According to this concept, the longer the open page is left idle, the less likely it will be accessed again before it needs to be closed and the bank precharged. Therefore, it would be better to prematurely close the page and precharge the bank so that the next page can be opened quickly when a data request comes along.

This BIOS option can be set to a variety of clock cycles from 0 Cycle to 48 Cycles. This determines the number of clock cycles open pages are allowed to idle for before they are closed and the bank precharged.

If you select Disabled, the memory controller will never precharge the open pages prematurely. The open pages will be left activated until they need to be closed for a bank precharge.

For general desktop use, it is recommended that you set this feature to 8 Cycles or 12 Cycles. It is important to keep the pages open for some time, to improve the chance of page hits. Yet, they should not be kept open too long as temporal locality dictates that the longer a page is kept idle, the less likely the next data request will require data from it.

For applications (i.e. servers) that perform a lot of random accesses, it is advisable that you select 0 Cycle as subsequent data requests would most likely be fulfilled by pages other than the ones currently open. Closing those open pages will force the bank to precharge earlier, allowing faster accesses to the other pages for the next data request. There's also the added benefit of increased data integrity due to more frequent refreshes.

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