Asus P4G8X P4G8X User Manual - Page 37

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 4GB system memory using 184-pin unbuffered ECC or non-ECC PC2100/ PC1600 DDR DIMMs, and allow up to 4.2GB/s data transfer rate. The following figure illustrates the location of the DDR DIMM sockets. DIMM_A1 DIMM_B1 DIMM_A2 DIMM_B2 104 Pins P4G8X ® P4G8X 184-Pin DDR DIMM Sockets 80 Pins 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. ASUS P4G8X series motherboard user guide 2-11