Asus P4PE 2.5.1 Overview, Notes on DDR technology, CPU FSB, DDR DIMM Type, Memory Frequency, Chapter 2: Hardware information

2.5System memory

2.5.1 Overview

The motherboard comes with three Double Data Rate (DDR) Dual Inline Memory Module (DIMM) sockets. These sockets support up to 2GB system memory using 184-pin unbuffered non-ECC PC2700/PC2100 (FSB533) or PC2100/PC1600 (FSB400) DDR DIMMs.

The following figure illustrates the location of the DDR DIMM sockets.

80 Pins

P4PE

104 Pins

P4PE 184-Pin DDR DIMM Sockets

This motherboard supports different memory frequencies depending on the CPU FSB (Front Side Bus) and the type of DDR DIMM.

CPU FSB	DDR DIMM Type	Memory Frequency
533 MHz	PC2700	333 MHz
	PC2100	266 MHz
400 MHz	PC2100	266 MHz
	PC1600	200 MHz

Notes on DDR technology

The DDR SDRAM technology evolved from the mainstream PC66, PC100, PC133 memory known as Single Data Rate (SDR) SDRAM. DDR memory however, has the ability to perform two data operations in one clock cycle, thus providing twice the throughput of SDR memory.

A DDR DIMM has the same physical dimensions as an SDR DIMM, but it has a 184-pin footprint compared to the 168-pin of the SDR DIMM. Also, a DDR DIMM is single notched while an SDR DIMM is double notched.

Therefore, a DDR DIMM is not backward compatible with SDR, and should be installed only in a socket specially designed for DDR DIMMs.

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