Asus P8B75-M LX P8B75-M LX User's Manual - Page 23

1.7 System memory 1.7.1 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: DIMM_A1 DIMM_B1 P8B75-M LX Channel Channel A Channel B Sockets DIMM_A1 DIMM_B1 P8B75-M LX 240-pin DDR3 DIMM sockets 1.7.2 Memory configurations You may install 1GB, 2GB, 4GB and 8GB unbuffered non‑ECC DDR3 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. • Due to Intel® 3rd generation processors' behavior, DDR3 2250 (and above)/2133/1866 MHz memory module will run at DDR3 2200/2000/1800 MHz frequency as default. • 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 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 any of the following: - Use a maximum of 3GB system memory if you are using a 32-bit Windows® OS. - Install a 64-bit Windows® OS when you want to install 4GB or more on the motherboard. • This motherboard does not support DIMMs made up of 512Mb (64MB) chips or less. • The default memory operation frequency is dependent on its Serial Presence Detect (SPD), which is the standard way of accessing information from a memory module. Under the default state, some memory modules for overclocking may operate at a lower frequency than the vendor-marked value. To operate at the vendor-marked or at a higher frequency, refer to section 2.4 Ai Tweaker menu for manual memory frequency adjustment. • For system stability, use a more efficient memory cooling system to support a full memory load (2 DIMMs) or overclocking condition. ASUS P8B75-M LX 1-13