What is interleaved memory?

[spacesurfer]

I just upgraded my memory from 1 Gb + 512 Mb to 1 Gb + 1 Gb.

When it was 1 Gb + 512 Gb, both were PC2-4200 and 533 mHz, CAS 4; both were single-channel.

Now, I have 1 Gb that's PC2-4200, 533 mHz and 1 Gb PC2-5300, 533 mHz.

When I turn on computer, during POST, it says PC2-4300, dual channel interleaved.

So, the questions are

1) Why does it say PC2-4300 when neither one is PC2-4300? It did this even when both were PC2-4200 and it does it now that one is actually PC2-5300.

2) Why does it say dual channel when my memory is single channel.

3) What does it mean when it says interleaved? When I had 1.5 Gb, it said something different (I can't remember than term) but now it changed to interleaved.

PC Specs:

Mobo: ASUS P5GDC-V

Memory: 2 X 1 GB (different brands)

[phkninja]

A basic explaination of Interleaved memory is, the memory on the motherboard is accessed as if it is one large block of memory e.g. the 2 RAM modules act like they are 1 RAM module. This reduces acess times and gives an overall speed boost.

Look at these for more info

Site 1

Site 2

Site 3

Tech Info on RAM

Edited May 11, 2007 by phkninja

[spacesurfer]

Great, thanks for sites. I understand now. So I have a good MOBO, then, since it supports interleaving.

I wish I could remember the term my MOBO used when I had a 1 Gb + 512 Mb memory installed.

Also, what about dual channel? Why is my MOBO saying dual channel when both my sticks are single channel.

[puntoMX]

Dual channel has nothing to do with the DIMMs you are using, it´s the motherbaord chipset, that one supports 128bit, dual channel, configurations of RAM.

Single channel would be 64bit. Dual channel vs Single channel will give you a verry small boost, like some 3% or so...

[jcarle]

Dual channel has nothing to do with the DIMMs you are using, it´s the motherbaord chipset, that one supports 128bit, dual channel, configurations of RAM.

Single channel would be 64bit. Dual channel vs Single channel will give you a verry small boost, like some 3% or so...

That not quite correct. A Dual Channel memory controller uses two 64-bit data channels, which gives the equivalent of 128-bits of bandwidth, but it is not natively 128-bits. The fact that the memory controller can use both memory channels at the same time is where the term Dual Channel comes from.

[#rootworm]

isn't that what he said?

[jcarle]

isn't that what he said?

There is a difference between is 128-bit and is equivalent to 128-bit.

Edited May 12, 2007 by jcarle

[#rootworm]

good job for saving the day!

[Zxian]

@rootworm - What's with the attitude?

jcarle is often just picky when it comes to specifics, but those details can mean a lot at times. It certainly doesn't hurt to have these things on file.

[#rootworm]

no attitude from me. he really did save the day. i ask you, where would MSFN be without "There is a difference between is 128-bit and is equivalent to 128-bit" ?

[nmX.Memnoch]

Looks like sarcasm to me....

There's a huge difference. From the original mention of 128-bit, someone not in the know could possibly assume that they would have 128-bit memory bandwidth with a single DIMM. jcarle's further explenation clarified that it uses two 64-bit channels, so in dual channel mode it is equivalent to 128-bit, but not truely 128-bit. Using a little common sense I could deduce that using a single stick would give me 64-bit memory bandwidth.

[puntoMX]

Yup 2x64bit, technically that is, but most people would say 128bit, so do "we" when we talk about 256bit 6800XT with 512MB for example, but that’s 2x128bit, 128bit like the 256MB version.

Any way, next time I will be more "exactly" with my "words", remember that English isn’t my native language .