PC Hardware in a Nutshell, 3rd Edition

Upgrading Memory in Pentium II/III/4, Celeron, and Athlon Systems

These systems are excellent candidates for memory upgrades. Early Pentium II systems often have only 16 MB of RAM. In the price-sensitive consumer Celeron market, many early systems shipped with only 16 MB, and some Celeron systems have been sold with only 8 MB. Expanding memory to 128 MB or more is the most cost-effective upgrade you can make. When upgrading memory in one of these systems, note the following issues:

• Some early Pentium II and Celeron systems use EDO SIMMs or DIMMs, but most use 3.3 volt 168-pin unbuffered JEDEC SDR-SDRAM DIMMs.

• Conserve DIMM sockets. A few motherboards have four DIMM sockets, most have three, and some low-end systems have only two. If you have the choice, always install one larger DIMM rather than two smaller ones that total the same amount of memory. Note, however, that older systems may not recognize large-capacity DIMMs or those that use 128-megabit or larger memory chips. In that situation, a BIOS upgrade may help, but the limitation is often hardcoded into the chipset.

• Most of these systems have nonparity memory installed, but can use either parity or nonparity DIMMs interchangeably. Unless you plan to install 512 MB or more, install nonparity DIMMs. We have been told that when using very large amounts of memory—more than 512 MB—memory errors introduced by cosmic rays make it worthwhile to pay the additional cost for parity/ECC memory and to accept the small performance hit ...