Asus CROSSHAIR IV FORMULA User Guide - Page 41

2.4.2 Memory configurations You may install 512 MB, 1 GB, 2 GB and 4 GB 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. • We recommend that you install the memory modules from the red slots for better overclocking capability. • Always install DIMMs with the same CAS latency. For optimum compatibility, we recommend that you obtain memory modules from the same vendor. • AMD AM3 100 and 200 series CPU support up to DDR3 1066MHz. • Due to different CPU margins, not all of AMD CPU can support up to DDR3 1600 and 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: - 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. 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 SPD. Under the default state, some memory modules for overclocking may operate at a lower frequency than the vendor-marked value. To operate at the vendormarked or at a higher frequency, see section 3.5 Advanced 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. ROG Crosshair IV Formula 2-15