Why is 12gb ram weird?

[Jaskaran498]

Hello
I have corsair vengeance 1x4gb+1x8gb=12gb.
I just saw people calling this ram number as "weird". And telling me to use either 8gb or 16gb.

Why is that sui?
What is problem with 12GB?

 

[omnisome]

You really shouldn't mix 4Gb and 8Gb memory, 12Gb is fine if you have 2x 6Gb, or 3x 4Gb (provided triple-channel is available).

 

[Jaskaran498]

You really shouldn't mix 4Gb and 8Gb memory, 12Gb is fine if you have 2x 6Gb, or 3x 4Gb (provided triple-channel is available).

Ok. But why?

 

[FinneousPJ]

It's just suboptimal regarding speed and compatibility.

 

[Jaskaran498]

Best answer selected by Jaskaran498.

 

[noob2222]

Hello
I have corsair vengeance 1x4gb+1x8gb=12gb.
I just saw people calling this ram number as "weird". And telling me to use either 8gb or 16gb.

Why is that sui?
What is problem with 12GB?

mixing ram sizes your likely forcing the cpu to run in single channel mode instead of dual channel. they can't share memory addresses for anything above the 8gb thats common between the two.

Rules to enable dual-channel mode
To achieve dual-channel mode, the following conditions must be met:

Same memory size (1 GB, 2 GB, 4 GB, etc.)
Matched DIMM configuration in each channel
Matched in symmetrical memory slots
Configurations that do not match the above conditions will revert to single-channel mode. The following conditions do not need to be met:

Same brand
Same timing specifications
Same speed (MHz)
Memory channel speed is decided by the slowest DIMM module populated in the system.

http://www.intel.com/support/motherboards/desktop/sb/CS-011965.htm

 

[w1zz4]

Maybe it's true for Intel, but on my previous build had 12GB of RAM (2X2 patriots el cheapos + 2X4 corsaire vengence, all DDR-1600 modules) with a AMD Phenom II 955 BE and it was Dual Channel and had no issue whatsoever. Motherboard was a Gigabyte GA-MA790FXT-UD5P.

 

[noob2222]

2x of each is fine, if you read the intel article it even said that. 1x 4gb and 1x 8gb will NOT RUN dual channel mode.

another explanation:

http://www.hardwaresecrets.com/article/Everything-You-Need-to-Know-About-the-Dual-Triple-and-Quad-Channel-Memory-Architectures/133/4

wich includes the AM3+ boards. pairs are pairs, doesn't matter the size, but has to be pairs, ie your 2x2 and 2x4.