[ The PC Guide | Systems and Components Reference Guide | Motherboard and System Devices | System BIOS | BIOS Settings | Advanced Chipset Features ]

There are a number of settings that control the timing of your system memory. For a full discussion on system memory timing, look here. Most setup programs now come with some sort of "automatic" setting that will determine what these parameters are for you. This is a "parent" setting of sorts that can be used to control the other individual timing settings on the screen. These parent settings normally come in one of two flavors:

• Dynamic Automatic Timing Setting: Some BIOSes have a fully automatic setting. When you put the DRAM Timing setting on "Auto", the chipset will detect what type of memory and cache you have at boot time and dynamically set all the timings for you automatically based on what it finds. This is the simplest way to ensure basically good performance from your system using any type of memory that it supports.
• Fixed Timing Based on Memory Speed: Other BIOSes, instead of having an "Auto" setting, let you choose from a selection of common memory speeds (or types) and then modify the individual timing settings based on your selection. Here, you may find settings like "70 ns", "60 ns", "EDO" and "Manual". "Manual" turns off the automated settings so you can tweak them yourself.

When you use the "Auto" setting (either fully automatic or by selecting a memory speed) the BIOS will normally "lock" the individual settings that are controlled by this one, to reflect the fact that they are being set automatically by the BIOS. To unlock the individual settings so you can change them, you normally must turn off the "Auto" setting, or select "Manual". The default in most BIOSes is to enable automatic timing settings.

Warning: In a system that dynamically sets timing based on the detected speed of your memory, you must take care when using memory of different speeds. You should generally put the slower memory in the first bank, often called Bank 0. Otherwise, the system may set the timing too fast for the slower chips.

Next: DRAM R/W Leadoff Timing

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