Hardware Reference
In-Depth Information
board brands and models to their databases. Therefore, if you know your system or
motherboard brand and model, you can find the memory that is recommended.
• Download and run analysis software that the memory module maker or a third party
provides. SiSoftware Sandra and similar programs use the SPD chip on each module
to determine this information.
• Consult your system documentation. I list this option last for a reason. If you have in-
stalled BIOS upgrades, you might be able to use larger and faster memory than your
documentation lists as supported by your system. You should check the latest tech
notesanddocumentation available onlineforyoursystemandchecktheBIOSversion
installed in your system to determine which memory-related features it has. A BIOS
upgrade might enable your system to use faster memory.
Adding the wrong modules to a system can make it as unreliable as leaving a defective
module installed and trying to use the system in that condition.
Note
Before upgrading an older Pentium (P5 class) system beyond 64MB of RAM, be sure your
chipset supports caching more than 64MB. Adding RAM beyond the amount supported by
yourL2cachecontrollerslowsperformanceratherthanincreasesit.PentiumIIandlaterpro-
cessors, including the AMD Athlon, Duron, and Sempron families, have the L2 cache con-
troller integrated in the processor (not the chipset), which supports caching up to 4GB and
beyond on most newer models.
Purchasing Memory
When purchasing memory, you need to consider certain issues. Some are related to the
manufacturing and distribution ofmemory,whereas others depend onthe type ofmemory
you are purchasing.
Suppliers
Many companies sell memory, but only a few companies actually make memory. Ad-
ditionally, only a few companies make memory chips, but many more companies make
memorymodulessuchasSIMMs,DIMMs,andRIMMs.Mostofthecompaniesthatmake
the actual RAM chips also make modules containing their own chips. Other companies,
however, strictly make modules; these companies purchase memory chips from several
chip makers and then produce modules with these chips. Finally, some companies don't
makeeitherthechipsorthemodules.Instead,theypurchasemodulesmadebyothercom-
panies and relabel them.
