Asus CROSSHAIR IV EXTREME, User Manual, Page: 40 / 172

2.4 System memory
2.4.1 Overview
The motherboard comes with four Double Data Rate 3 (DDR3) Dual Inline Memory
Modules (DIMM) sockets.
A DDR3 module has the same physical dimensions as a DDR2 DIMM but is
notched differently to prevent installation on a DDR2 DIMM socket. DDR3 modules
are developed for better performance with less power consumption.
The figure illustrates the location of the DDR3 DIMM sockets:
Recommended memory configurations
One DIMM:
Install one memory module in any slot as a single-channel operation.
Two DIMMs (dual-channel operation):
Four DIMMs (dual-channel operation):
2-14 Chapter 2: Hardware information