X.M.P. DIMM support

[Doggie52]

Hello!

In the manual for my ASUS P7P55D-E LX, in the Memory Configurations section, the following note appends the instructions on how to install the memory:

Due to Intel spec definition, X.M.P. DIMMs are supported for one DIMM per channel only.

What does this mean? Does this mean that I only can use one stick of RAM per channel, meaning that I can't run two sticks in Dual-Channel mode?

If I buy two 2GB sticks of RAM with the X.M.P. feature, can I turn this on/off inside the BIOS and thus use them in Dual-Channel mode anyway?

How is the performance of X.M.P. RAM versus Dual-Channel RAM?

Thanks in advance,

Doggie52

[Tripredacus]

It looks like the XMP spec is for overclocking your memory. It may be that this chipset cannot handle the additional voltage used by dual channel (think 3 sticks vs 6 sticks of RAM) when overclocking? Since this is fairly recent for Intel, it may become possible in future chipset revisions. It also looks like the ability to use XMP memory is highly dependent on the CPU you are using. Some say you need an i7 Extreme series CPU.

[Guest]

Maybe it's related to the necessity of increasing the memory's command rate when using more than one DIMM per channel?

Edited February 9, 2011 by 5eraph