Asus P55SP4 P/I-P55SP4 User's manual - Page 25

2 P/I-P55SP4 User's Manual Upgrading System Memory This section explains how to install system memory. There are instructions on how to configure and install memory and an explanation of the technical specifications required. System DRAM is the main source of data for the CPU. Data remains stored in DRAM as long as the system is turned on, and is lost when you turn it off. The Level 2 cache memory is Static RAM (SRAM), which is faster than DRAM memory. When the CPU looks for data, it first searches the cache. If the information is not there, the search continues in the DRAM. With this design, the CPU looks in the fastest source of data first, which lets it operate as fast as possible. The DRAM subsystem uses memory chips permanently mounted on small circuit boards to form "SIMMs" (Single In-line Memory Modules). The memory chips have a speed rating that is measured in nanoseconds (ns). This mainboard requires either Fast Page Mode (FPM) DRAM or Extended Data Output (EDO) DRAM with a speed of at least 70ns. This mainboard can use 72-pin SIMMs in four sizes from 1MB up to 128MB (megabytes). Depending on the combination of modules you use, you can install between 2MB and512MB. The 32-bit modules used for this board come with memory chips on either one or both sides of the module. IMPORTANT: Do not use SIMM modules with more than 24 chips per module with this mainboard. Modules with more than 24 chips exceed the design specifications of the memory subsystem and will cause unreliable operation. DO NOT use 32 or 36-chip modules with this mainboard. 2 - 6