Double and Single Sided RAM - Explain!

[SimonTW]

Hello All,

So I've managed to confuse myself with the question of if RAM is single or double sided!

I have done a fair amount of google work/forum searching, yet have seemed to find conflicting answers.

My first conclusion with regards to RAM being double or single sided was that double sided had memory modules on both sides of the PCB, whilst single only had them on one side!

However, as I was helping a friend with some problems he was having, I wanted to make sure this was the case before he ended up spending his money on the back of my advice!

The first result I came across was a Wikipedia article that stated the single/double sided name was not a physical characteristic, but refered to how the computer itself 'views' the memory, meaning single sided RAM can have memory chips on both sides of the PCB. Other results though suggest my original conclusion is indeed correct, and it really is as simple as it sounds!

So I ask you, OcUK, what is correct? One? The other? Both? Or something entirely different?!

 

[simbady]

I have never heard of double and single sided RAM but all the RAM i have used has RAM chips on both sides.

 

[PCZ]

If you have a dimm with 8 chips on one side it is single sided.
Could be 9 if it is ecc.

Generally
A diim with 4 chips per side will also be single sided.
Electrically they will all be connected to the same side, but physically mounted on both sides.
This can be done to make low profile simms, the chips are mounted horizontally so the simm has a low height.

A dimm with 8 or more chips per side will be double sided electrically.
The computer will see 2 banks of memory in that dimm slot.

Note:
This doesn't mean dual channel mode though most chipsets require 2 slots to do that.

Some chipsets can interleave the 2 banks on double sided dimms to increase memory throughput.