Asus Xeon Tower/5U Rackmount Server AP1710-S5 - Manual (Page 26)

Chapter 2: Hardware setup 2-8
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 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.
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
PRL-DL ®
PRL-DL 184-Pin DDR DIMM Sockets
80 Pins
104 Pins
DDR1 DDR2 DDR3 DDR4
2.4 System memory
The motherboard comes with four Double Data Rate (DDR) Dual Inline
Memory Module (DIMM) sockets. These sockets support up to 4GB
system memory using 184-pin registered PC2100/PC1600 DIMMs with
Serial Presence Detect (SPD) and Error Check and Correction (ECC).