I recently found out that I had my 2 RAM sticks in apparently a ‘wrong position’ (side-by-side).
Someone pointed out that they needed to be placed in alternate slots.
I read my motherboard manual, I tried doing as much research as possible about this but all I got from that is that the alternate placement puts the RAM in ‘dual-channel’ mode and is somehow better.
I haven’t got any clear-cut/simple explanations as to WHAT ‘dual-channel memory’ means or WHY it’s better.
Someone please ELI5.
In: Technology
If you have 16gb of ram rated for 1800mhz (for example) running it in single channel will run it at 900mhz if running in dual channel it will run at the rated 1800 mhz as long as your mobo can run it at that speed.
Besides saying “it’s faster” like this is ELI2 or something, the actual reason it’s faster that could be understood by a five year old is as follows:
RAM has Memory and Speed. Memory is how much work it can do, and Speed is, well, how fast it can do that work. It’s much easier to increase Memory (4/8/16/32 GB) than it is to increase speed (2000mhz~3200MHz). If you only have the option of one 32GB/2500 MHz or two 16GB/2200MHz for example, the two would be better if your motherboard supports dual-channel. With dual channel, it can use both at the same time, effectively making the two 32GB/4400MHz.
Just circuitry and the way they always wire dual channel memory slots. Think of each channel of memory access being the connection to each set of banks/slots. So channel 1 = slots 1 and 2, channel 2 = slots 3 and 4.
If you put two 4 GB sticks in slots 1 and 2, both are being accessed via a single 64 bit channel.
If you put one each in slots 1 and 3, you have a dedicated 64 bit channel for EACH 4 GB ram module.
In theory (depending on what manufacturer’s benchmark report you read) dual channel RAM should give you a 10-15% improvement in memory access, but in practice (and due to a lot of other factors that make it hard to isolate) you get about 5-10% increase by utilizing dual channel.
It means that you can read and write to both ram sticks at the same time, in ELI5 terms.
If you only have a single channel architecture then you can only read and write data to a single stick of ram at any given time, dual channel means you can read and write to 2, quad channel means 4, six channel means 6, eight channel means 8, triple channel means 3…
Regarding performance improvements, during gaming benchmarking there was a negligible improvement and the reason is that very rarely do you need to use so much memory in the first place so it usually is all contained on a single chip. For processes with high memory demand (like say rendering a 3d animation) it can offer more improvements at times but won’t necessarily provide a detectable improvement.
The way that multiple memory modules works is that all the modules are connected to the same wires. So when the memory controller sends a command it goes to every memory module at once. The only difference is a few wires which is used to select which module should receive the command. This way you only need about 300 wires to connect all your memory to the memory controller on your processor. The problem being that the memory controller can only access one module at a time which reduces the bandwidth. So instead of just using one channel of about 300 wires the memory controller will use two channels of a total of 600 wires. Each channel will be connected to a different set of memory slots, typically placed on each side of the processor socket or at lest distanced a bit apart to allow all the wires to route through. This allow you to get double the bandwidth between your memory and the processor but still gives you the ability to have multiple memory modules per channel to increase capacity.
Imagine you have a room with two narrows flies of stairs with two blackboards behind them. One with maths tasks written on it and an empty one.
These tasks are too hard for you to solve but you have a disabled friend who is very good at maths and loves to solve these kinds of tasks.
Unfortunately they can’t get up from their wheelchair and you can’t see the tasks from the bottom of the stairs. Carrying them up the stairs isn’t possible either because they’re so narrow.
Your disabled friend would really like to solve these tasks though and would also like you to write their solutions onto the other board.
An easy solution is that you walk up to the first board, memorize a task, go back down, recite it to your friend and they then solve it. After they solved it they tell you their solution and you go to the other board to write it down.
That process obviously takes a bit of time but your friend wants to hear many many more math puzzles as fast as possible. You could try to run faster (clock speed), memorize faster, recite faster and write down faster (timings) but there’s a limit to how fast you can do these things without tripping or making errors (crashes, memory errors).
What could be done to speed this process up even further now? You call a second friend to help you out.
The stairs are very narrow of course which means only one of you can get up to each blackboard at a time, so you split the work; you memorize math tasks and the second friend writes down the solutions your disabled friend tells them.
This way you’d already be on your way to pick up the next question while your disabled friend is still telling your second friend what solution they should write down and while you’re reciting the math question to your disabled friend, your second friend is writing down the answer to the previous one which makes the whole process faster.
However some of the tasks are more complex and you can only memorize parts of them each run which means you sometimes have to run multiple times before your disabled friend has the full task to solve. The second friend can’t help much in those cases because they have to wait for you to give the disabled friend the whole tasks before they can solve it and tell the second friend who then goes to write down the solutions.
Having the two RAM sticks configured in dual channel mode is like calling over the second friend.
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