3GB of memory in a laptop.

[jawknee530]

I've started seeing laptops advertised with 3GB of memory in a dual channel configuration. I thought that in order for memory to work in dual channel the DIMMs had to be the same size. How do laptops work in dual channel with only two slots. Are they two 1.5GB sticks or a 2GB and a 1GB?

 

[MrX8503]

There are no 1.5gb dimms.

I think the laptops are using a 2gb+1gb stick.

I'm not sure if i'm right on this or not, but I don't think it would be running in dual channel. Honestly 3gb is more of a marketing gimmick.

 

[Cheex]

4 slots = 2x1GB + 2x512MB = 3GB Dual Channel

 

[AmberClad]

That actually what I originally thought too, but after discussing upgrading our work laptops with a co-worker, it turns out that (at least in our case), the laptops only have two so-dimm slots.

 

[Cheex]

In that case, it must be running in Dual Channel Flex Mode, instead of the 'rightful' and true Dual Channel Interleaved Mode.

 

[jawknee530]

amberclad is right. they only have two slots in the laptops. whats the difference from flex mode and interleaved mode? im off to wikipedia to find out but its almost always easier to have it explained.

 

[Cheex]

Here is the Wikipedia link:

Dual Channel Architecture

Regular dual channel, where everything (RAM size, speed, etc.) is perfectly matched is what is called Dual Channel Interleaved Mode.

The link explains Flex Mode.


:thumbsup:

 

[Mondoman]

I'm running my notebook with 1x2GB SODIMM and 1x1GB SODIMM in Flex Mode - it works great! Since the T7200 CPU's FSB is 667MHz, and the RAM is running at DDR2-667 speed, even the part of RAM running in single-channel mode has enough throughput to fully saturate the FSB bandwidth.