ASUS p8z68-m pro User Manual

1-18

Chapter 1: Product introduction

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.

•  Always install DIMMs with the same CAS latency. For optimum compatibility, we 

recommend that you obtain memory modules from the same vendor. 

•  According to Intel CPU spec, DIMM voltage below 1.65V 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 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 (4 DIMMs) or overclocking condition.