Asus M5A99X EVO R2.0 M5A99X EVO R2.0 User's Manual - Page 25

Memory configurations You may install 1GB, 2GB, 4GB, and 8GB unbuffered ECC and 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. • 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. • Memory modules with memory frequency higher than 2133MHz and their corresponding timing or the loaded XMP profile is not the JEDEC memory standard. The stability and compatibility of the memory modules depend on the CPU's capabilities and other installed devices. • Due to the CPU spec., AMD AM3 100 series CPUs support up to DDR3 1066MHz. With ASUS design, this motherboard can support up to DDR3 1333MHz. • When overclocking, some AMD CPU models may not support DDR3 1600 or higher frequency DIMMs. • 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: a) Use a maximum of 3GB system memory if you are using a 32-bit Windows OS. b) Install a 64-bit Windows OS when you want to install 4GB or more on the motherboard. c) For more details, refer to the Microsoft® support site at http://support.microsoft. com/kb/929605/en-us. • This motherboard does not support DIMMs made up of 512Mb (64MB) chips or less (Memory chip capacity counts in Megabit, 8 Megabit/Mb = 1 Megabyte/MB). • 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 3.4 Ai Tweaker menu for manual memory frequency adjustment. • For system stability, use a more efficient memory cooling system to support a full memory load (4 DIMMs) or overclocking condition. Chapter 1 ASUS M5A99X EVO R2.0 1-11