Technology Question about RAM memory (dual channel, performance)

[Preach]

So I am doing additional research on how various computer part technologies work. I've gone through northbridge chipsets, CPU sockets and CPUs, GPUs, hard drives I am currently still researching, and I've started looking into RAM.

I am trying to understand single, dual and trippel channel RAM. Principally, I assume dual channel causes lower latency and higher performance the same way RAID does for a harddrive - two units processing the data instead of a single unit, each of them doing half the job simultanously. So I assume more RAM channels causes a (marginal) performance advantage. Is this true? I am trying to decide whether to go with dual or triple channel memory, and then I'm wondering, what happens then if I buy 4 of the same memory stick? Do I get 2x dual channels, or would they be working over dual channels in pairs? If I go triple channel and decide to expand with an extra memory stick later on, is there even such a thing as quad-channel? Where does the added fourth memory stick fit into the script with the already installed triple channel memory?

Furthermore, how much does bus frequency matter? How big of a difference is there in performance between a 1600mhz stick and a 2100mhz one? Say if a figure exists in the format of an estimated percentage? So far, anything I've read suggests I should go with 1600mhz memory as anything above requires proper cooling which will not fit together with the rather large CPU cooler I am getting, and that the performance gain is so marginal in comparison with the price that even people with special needs should consider twice.

 

[Preach]

The "2x dual channels / two dual channels in pairs"-bit might be a little bit unclear, but I have a hard time explaining what I mean, so I'll try again.

I imagine it working in one of two possible ways, either:

RAM 1 \
RAM 2 - These two represent one separate dual channel consisting of two sticks

RAM 3 \
RAM 4 - These two represent another separate dual channel in addition to the first one

for a total of four channels

or:

RAM 1 \
RAM 2 - These two represent a pair of one channel

RAM 3 \
RAM 4 - These two represent a pair of the other channel, thus making it "dual"

for a total of two channels

I am assuming it's the second "model". Got any thoughts masta?

 

[Cooper]

Not sure what you're asking lol, but there's no quad channel, and if you put 2 sticks in a triple channel, it'll run as dual channel.

I only really know about dual channel, but it's 2 banks of 2 so you have:
BANK 0 - RAM 1
BANK 0 - RAM 2

BANK 1 - RAM 3
BANK 1 - RAM 4

and the DIMMs within each bank should be matched. I assume triple channel just added a slot to each bank?

 

[masta247]

Yes, so basically if you have 4 identical pieces of ram and pair them in dual channel you have 2 separate dual channel units.
To make it simple two sticks of ram in dual channel act like a single ram taking advantage of speed of both, sort of like with RAID.
If you have two sets of those they act like two separate units of dual channel sticks. Or two pairs of RAM running in dual channel mode.
If you have 2 sticks running in dual channel and add a third stick the 2 will run in dual channel and the third one will run separately possibly slowing down your system (depends on the memory controller) since your ram will always slow down to the slowest unit. So either go for 2 sticks or multiple of 2 sticks (in which case they will act like a few separate units of dual channel memories).

There's no such thing as quad channel yet. Triple channel works with Intel's semi-new processors but the difference between triple channel and dual channel is very small, a few percent in memory bandwidth at most. It saves you from lost performance if you decide to use 3 memory sticks though.
Now Sandy Bridge processors (which I assume you're getting) don't work in triple channel anyway.
16000mhz 2x2sticks in dual channel on Sandy Bridge are much better than any 3x1 stick in triple channel because of superior memory controller in Sandy Bridge. If I were you I'd go for 4, 6 or 8 sticks (depending on your needs) of ram in dual channel.

1600mhz is very fast anyway and there's no point in going any higher at the moment since it's the fastest stable, commercially available speed. Faster memories are factory made 1600mhz sticks that are overclocked later that were not made to work that fast in the first place.
You'd be good with 1600mhz ram but go with as low timings as possible so you can overclock it higher whenever you want too. Lower timings also give you a bit of a performance advantage.

Edit @ cooper - yes.
However since you mentioned that I want to add that motherboards require ram to be placed in proper slots which depends on the motherboard and it's important to remember, because while most older motherboards are structured like this:

slot 1 - dual channel 1
slot 2 - dual channel 1

slot 3 - dual channel 2
slot 4 - dual channel 2

There are many motherboards which work like this:

slot 1 - dual channel 1
slot 2 - dual channel 2

slot 3 - dual channel 1
slot 4 - dual channel 2

Usually they are properly colored to indicate that - same colored slots means that corresponding dual channel sticks should be placed in them.
The reason I mention is that people really often make a mistake and put their RAM in wrong slots losing the advantage of dual channel.

 

[Preach]

I was misunderstood, but I get it now. Thank you sirs and sirettes (cooper).