PC Hardware in a Nutshell, 3rd Edition

Upgrading Memory in Pentium Pro and Pentium-Class Systems

Pentium Pro and P54C/P55C Pentium-class systems, including those with an AMD K6 or higher, are too old to be good upgrade candidates, but many such systems are still used as firewalls and fax servers, and for other appliance duties, where it may make sense to extend their useful lives for another year or two by installing a memory upgrade. When upgrading memory in a Pentium or Pentium Pro, note the following issues:

• Try to install the memory identical to that already installed. Early Pentiums and most Pentium Pros use 72-pin SIMMs, but either type of system may use DIMMs in addition to or instead of SIMMs. Existing memory may be FPM, EDO, or SDRAM. Many systems can use different memory types—e.g., FPM or EDO—but do not allow mixed types. If you have a choice, install SDR-SDRAM DIMMs. Even PC66 DIMMs work fine in systems this old, and most systems of this type yield better memory performance with SDRAM than with older memory styles.

• Most such systems have nonparity memory installed. Some do not support parity memory. Pentium Pro systems often have parity memory installed, and may use ECC. Some systems support parity or nonparity memory, but do not allow mixed types. Others accept parity or nonparity RAM interchangeably, but disable parity if any nonparity modules are installed. For SIMM-based systems, count chips to determine memory type. For DIMM-based systems, locate the identification number on a module and check the ...