Problem recognizing full amount of RAM

[alexgoh]

Hey everyone, recently I purchased another 8Gb of Kingston HyperX RAM and installed it into my computer which already had 4Gb. However, Windows 7 Pro 64-bit says 12Gb installed (6Gb usable). I think it is an issue with my motherboard but I'm not too proficient with this so I'd like to seek some advice and whether this can be overcome. My system specs are as follows:

Intel i7 870 @ 2.93 GHz
Asus P7P55D-E
Asus ATI 6870
Kingston HyperX CL7 4Gb Kit (Originally purchased)
Kingston HyperX CL9 8Gb Kit (Purchased today, the shop assistant told me that they no longer bring in the CL7 due to it being too costly. They told me my CL7 would function as a CL9 once I put my new kit in)

As mentioned before, I'm running Windows 7 Professional 64-bit version.

Thank you very much for your help!

 

[Doctor John]

[LEFT][FONT=Verdana]You could try opening msconfig>boot>advanced options and make sure "Maximum memory" is unchecked?[/FONT][/LEFT]

 

[alexgoh]

Hey there, just checked it out and it's already unchecked!

 

[Doctor John]

Oh dear. I thought that the main point of 64-bit was to recognise big RAM - have you checked the relevant BIOS settings? Some systems require large (>4GB) memory to be remapped in BIOS?

 

[alexgoh]

Uh I'm not too sure about that. What should I be looking out for under my BIOS?

 

[LNCPapa]

How do you have your DIMMs paired up?

 

[Cinders]

I'm pretty sure he has the memory in the wrong slots. From page 2.4.2 of the motherboard manual:

" 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."

That means you probably have both of the memory sets paired up, the CL7 set is pair up and the CL9 set is paired up when you should have one of each set paired with the other set, so that each channel has 6GB of memory. Instead one channel has 4GB of memory and the other channel has 8GB of memory.

The first DIMM slot closest to the processor should be occupied with a 4GB dimm, the second DIMM slot should be occupied with a 2GB DIMM, the third DIMM slot should be occupied with a 4 GB DIMM and the fourth DIMM slot should be occupied by the final 2GB DIMM. If that didn't work I'd put a 2GB DIMM in the first slot and a 4GB DIMM in the second and so on.

If all of that doesn't work, then I'd guess the memory is incompatible.

 

[alexgoh]

Ah, originally my pairing as 4Gb, 2Gb, 4Gb, 2Gb. I've just changed it to 2Gb, 4Gb, 2Gb, 4Gb and it seems to work! Thank you very much everybody for the amazing help!

 

[Doctor John]

Aha, good call, Cinders, sorry Alexgoh, I think I was trying to swap the slots round frim BIOS!

 

[Cinders]

Glad we could help