Two x-GB RAM cards ##\neq## one 2x-GB card?

[Wrichik Basu]

Say you have a computer (desktop or laptop), and you have, say, 8GB total of RAM. There are two options to get a total of 8GB:

1. Use two 4GB cards.
2. Use one 8GB card.

The mechanic who services our desktop says that using two RAM cards is not equivalent to using one single card. He says, "How much of the other 4GB will be actually used by the CPU is questionable."

Is this correct? How does the CPU share memory between two (or more) RAM cards?

 

[Rive]

This question cannot be answered correctly without knowing the type of CPU and possibly the motherboard and the OS.

Some OS has (had) memory limitations and some motherboards/CPUs can do tricks like multi channel RAM access which will be faster in case two (three) sticks are used instead of one.

 

[Wrichik Basu]

This question cannot be answered correctly without knowing the type of CPU and possibly the motherboard and the OS.

Take my PC with Windows 7 32-bit, Intel i3 processor, and motherboard Asus P7H55M-LX.

By the way, how will you determine with the information you requested?

 

[Rive]

Take my PC with Windows 7 32-bit, Intel i3 processor, and motherboard Asus P7H55M-LX.

The OS has a memory limit of 4GB, but you have to deduct the memory of the graphic card from that. 2X4GB or 1X8GB - what the OS will see is only 4GB anyway.
The CPU and the MoBo can support dual channel, so it'll be a bit faster if you try it with 2X4GB (if the type/frequency of the memory sticks are the same).

IF you get rid of the 32 bit OS and switch to 64bit one then having 8GB memory will be better than the benefits of dual channel. But as things are now the best would be a second 8GB stick (of the same kind) and a 64 bit OS...