Asus M4A78-VM IN SI User Manual - Page 12

1.3 Central Processing Unit (CPU) This motherboard comes with an AM2+ / AM2 socket designed for AMD® Phenom™ x4 / Phenom™ x3 / Athlon™ x2 / Athlon™ / Sempron™ processors. It also supports AM3 CPUs including Phenom™ II / Athlon™ x4 / Athlon™ x3 / Athlon™ x2 processors. The AM2+ / AM2 socket has a different pinout from the 940-pin socket designed for the AMD Opteron™ processor. Use a CPU that is designed for the AM2+ / AM2 socket. 1.4 System memory 1.4.1 Overview This motherboard comes with two Double Data Rate 2 (DDR2) Dual Inline Memory Modules (DIMM) sockets. The figure illustrates the location of the DDR2 DIMM sockets: Channel Channel A Channel B Sockets DIMM_A1 DIMM_B1 1.4.2 Memory configurations You may install 512MB, 1GB, 2GB, and 4GB unbuffered ECC and 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 the single-channel operation. • Always install DIMMs with the same CAS latency. For optimum compatibility, we recommend that you obtain memory modules from the same vendor. • Due to the memory address limitation on the 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 do either of the following: - Install a maximum of 3GB system memory if you are using a 32-bit Windows® OS. - Use a 64-bit Windows® OS if you want to install 4GB or more memory on the motherboard. • This motherboard does not support DIMMs made up of 256 megabits (Mb) chips or less. The motherboard supports up to 8GB memory modules on Windows® XP Professional x64 and Vista x64 editions. You may install a maximum of 4GB DIMMs on each slot. 1-3 Chapter 1: Product introduction