Ok, I think we are
I am just confused on the naming of the channels/slots.
In this example, that board is set up the same as yours. Ill use Channel A and Channel B, and slot 1 and slot 2 for each channel.
Ok, I made a mistake on the channels/slots, which is probably why Im confusing you. Slots 1 and 2 are on channel A. Slots 3 and 4 are on channel B. You want to place DIMMs in slots 1 and 3 to enable dual channel mode, so that there is a stick in each channel (at least). The the amount of RAM in slot 1+2 should match that of slot 3+4, with ideally 1 matching 3 and 2 matching 4.
I read somewhere that older AMD systems would be slots 1 and 3 for channel A and 2 and 4 would be channel B, which is where I think I started to explain things backwards.
If you have RAM with different speeds, it will run at the speed of the slowest RAM and widest timings. It cannot run RAM at different speeds. If you bought 1333 MHz RAM and 7500 MHz RAM, they would ALL run at 1333 MHz until you specify otherwise. If you change it in BIOS, you change it for ALL RAM slots.
And programs dont use up certain channels. That is done by the memory controller. The programs just says "I need this information placed on RAM/taken from RAM" and the memory controller deals with the RAM. You dont need to run more than one program to use dual channel mode as that would imply.
Edit: To clarify more:
Honestly it doesn't really make sense if the DIMMS are in different banks since they should operate independent of each other shouldn't they?
Think of a motherboard with only 2 slots that can run in dual channel mode. One slot would be for Channel A and one for Channel B. If you have a 2 GB stick, and a 1 GB stick, 1 GB would run in duan channel mode, and the extra 1 GB would run in single channel mode. The motherboard can only access 64 bits from each channel during a cycle. Each channel DOES NOT operate independently, they have to have the same timings, speed, and memory size, and any memory that is not matched by the other side will not run in dual channel mode.
I understand if I try to use a 4gb stick in the same bank as a 2gb stick then only 4GB will operate in dual channel while the left over 2gb will operate in single channel... However does that apply to different banks operating with different capacity sicks, yet the same capacity in each respective bank?
That, I do not have an answer to...
4/2/4/2 would be your best bet to have everything run smooth and use all 12 GB of RAM. Channel A has 4/2 and Channel B has 4/2 so it exactly matches it. I cant guarantee that it will use all 6GB in dual channel mode per channel, but that is your best bet.
Actually, if you had a 4 GB stick in slot 1 and a 2 GB stick in slot 2, it would be able to use all 6 GB, but it wouldn't be in dual channel mode. So I would imagine 4/2 in each channel would work as well. Just dont do something like 4/2/1/4
Edit 2: To further elaborate:
From your mobos manual from the Asus website (P8P67 Pro):
You may install varying memory sizes in Channel A and Channel B. 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.
In the picture, Channel A is made up of slots 1 and 2, and Channel B is made up of slots 3 and 4.Edited by mad0314 - 7/21/11 at 5:55pm