12GB RAM installed but only 6GB is usable?

[dwrlewis95]

So i had 2 x 2GB Samsung RAM installed, and have just added another 2 x 4GB corsair RAM. All 12GB are detected, but only 6GB is usable?

Here are my specs:
Intel core i5 750
ASUS P7P55D Intel P55 motherboard
ASUS Geforce GTX 560ti graphics card
Corsair 650W power supply
2 x 2gb Samsung DDR3 RAM 1333mhz
2 x 4gb Corsair DDR3 RAM 1600mhz

 

[herrwizo]

I would give it a try with only 2x4 and see how much is usable. Mixing RAMs is never a good idea.

 

[dwrlewis95]

Well strangely enough i took the 2 x 4GB back out for comparison, and it says 4GB (2GB usable) which it never did beforehand, with the original 2 x 2GB it allowed the full 4GB.

 

[herrwizo]

Well strangely enough i took the 2 x 4GB back out for comparison, and it says 4GB (2GB usable) which it never did beforehand, with the original 2 x 2GB it allowed the full 4GB.

Test each stick separately (alone) and see whether they all work and how much you get reported for each one.

 

[dwrlewis95]

Every single one gives half its value usable when used individually.

 

[Vlad Rose]

That may be related to your motherboard not supporting RAM at that particular density then. By chance, are all the RAM chips on only one side of the memory stick? I had a similar problem years back.

 

[herrwizo]

That may be related to your motherboard not supporting RAM at that particular density then. By chance, are all the RAM chips on only one side of the memory stick? I had a similar problem years back.

He already stated that 2x2 were correctly recognized until he added 2x4 next to them. And now it won't even recognize the other modules, as far as I can see.

@OP: apparently, all modules are working, just incorrectly recognized.

First, clear CMOS on the motherboard (remove the battery and return it after a minute or so, or use a CLR_CMOS jumper next to the battery).

I would then try with, for example, 1x4 GB module and test it in all slots, to see whether the first and third slots are the issue or not. If you get all 4 GB recognized on 2nd and 4th slot, but not on 1st and 3rd, we can investigate further.

Please list the exact model of 4GB and 2GB modules if possible.

 

[Vlad Rose]

That may be related to your motherboard not supporting RAM at that particular density then. By chance, are all the RAM chips on only one side of the memory stick? I had a similar problem years back.

He already stated that 2x2 were correctly recognized until he added 2x4 next to them. And now it won't even recognize the other modules, as far as I can see.

He did state in the line above that "Every single one gives half its value usable when used individually.", which makes me figure that they aren't correctly recognized.