Asus P5QL-EM User Manual - Page 22

Mode One DIMM Two DIMMs Three DIMMs Four DIMMs DIMM_A1 DS/SS - DS/SS DS/SS SS SS DS/SS SS DIMM_A2 DS/SS DS/SS DS/SS SS SS DS/SS SS DIMM_B1 DS/SS DS/SS DS/SS DS/SS SS SS SS DIMM_B2 DS/SS DS/SS DS/SS DS/SS SS SS SS • When using only one memory module, start installing the DDR2 DIMM from slot DIMM_A1 or DIMM_B1 for better overclocking capability. • For dual-channel configuration, you may: - install identical DIMMs in all four sockets OR - install identical DIMM pair in DIMM_A1 and DIMM_B1 (yellow sockets) and another identical DIMM pair in DIMM_A2 and DIMM_B2 (black sockets) • Always use identical DDR2 DIMM pairs for dual channel mode. For optimum compatibility, we recommend that you obtain memory modules from the same vendor. 1.7.2 Memory configurations You may install 256MB, 512MB, 1GB and 2GB unbuffered non‑ECC DDR2 DIMMs into the DIMM sockets. • You may install varying memory sizes in Channel A and Channel B. The system maps the total size of the lower-sized channel for the dual-channel configuration. Any excess memory from the higher-sized channel is then mapped for single-channel operation. • Always install DIMMs with the same CAS latency. For optimum compatibility, it is recommended that you obtain memory modules from the same vendor. • Due to the memory address limitation on 32-bit Windows OS, when you install 4GB or more memory on the motherboard, the actual usable memory for the OS can be about 3GB or less. For effective use of memory, we recommend that you install a 64-bit Windows OS when having 4GB or more memory installed on the motherboard. • Due to chipset limitation, this motherboard only supports up to the total of four ranks (four sides in total) of RAM at max. • This motherboard does not support DIMMs made up of 256 megabit (Mb) chips or less. 1-12 Chapter 1: Product introduction