Asus Motherboard NR-LSR - Manual (Page 34)

2-8 Chapter 2: Hardware information
2.5 System memory
2.5.1 Overview
The motherboard comes with four Double Data Rate (DDR) Dual Inline
Memory Module (DIMM) sockets. These sockets support up to 8GB
system memory using 184-pin registered PC2100/1600 DDR DIMMs with
Serial Presence Detect (SPD) and Error Check and Correction (ECC).
A DDR DIMM is keyed with a notch so that it fits in only one direction.
DO NOT force a DIMM into a socket to avoid damaging the DIMM.
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. For example, a
200MHz DDR DIMM will support a 100MHz memory bus, and a 266MHz
DDR DIMM will support a 133MHz memory bus.
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.
DDR Data Transfer Rate DDR Base Frequency
266MHz 133MHz
200MHz 100MHz
NR-LSR
®
NR-LSR 184-Pin DDR DIMM Sockets
80 Pins 104 Pins