Asus H170I-PRO/CSM User Guide - Page 18

1.4 System memory Overview This motherboard comes with two Double Data Rate 4 (DDR4) Dual Inline Memory Module (DIMM) sockets. The figure illustrates the location of the DDR4 DIMM sockets: DIMM_A1 DIMM_B1 DIMM_B1 DIMM_B2 Channel Channel A Channel B Sockets DIMM_A1 & DIMM_A2 DIMM_B1 & DIMM_B2 • 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 optimal compatibility, we recommend that you install memory modules of the same version or date code (D/C) from the same vendor. Check with the retailer to get the correct memory modules. • Due to Intel® chipset limitations, DDR4 2133MHz and higher memory modules on XMP mode will run at the maximum transfer rate of DDR4 2133MHz. • According to Intel® CPU spec, DIMM voltage below 1.35V is recommended to protect the CPU. • 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 if you want to install 4GB or more on the motherboard. - For more details, refer to the Microsoft® support site at http://support.microsoft. com/kb/929605/en-us. • Memory modules with memory frequency higher than 2133 MHz and its corresponding timing or the loaded X.M.P. Profile is not the JEDEC memory standard. The stability and compatibility of these memory modules depend on the CPU's capabilities and other installed devices. • 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. • For system stability, use a more efficient memory cooling system to support a full memory load (2 DIMMs). • Refer to www.asus.com for the latest Memory QVL (Qualified Vendors List) 1-10 Chapter 1: Product introduction