So is 3GB not a dual channel setup?

I am not sure if it's different with laptops or not but I know when you have 2 slots, both sticks have to match to run in dual channel. So when I order 3gb of ram I am sure its' a 1gb and 2gb setup.

Does this mean I am messing myself over for not going with 4?

 

You are not messing yourself over, but remember there are two types of dual channel.

Asymmetric Dual Channel and Symmetric Dual Channel.

When you order 3GB of ram with 1x1GB stick and 1x2GB stick, you only get asymmetric dual channel with only 1GB being utilized.

Though when you order 2x2GB sticks, you get to use 2GB symmetric dual channel in which the full dual channel is utilized.

Your not messing yourself up by not going with 4, but you would get better performance if you went with 2x2GB.

 

-Ignore or Delete-

 

1 RAM module is single channel

2+1=3gb is assymetrical dual channel.

2+2=4gb is symetrical (true) dual channel

Assuming you have the santa rosa platform:

Single channel PC-5300 667mhz will give you a peak bandwidth of 5.3gb/s
(667mhz * 8bytes * 1 channel = 5.3gb/s)

Asymetrical dual channel will give you a peak bandwidth 8gb/s. Intel 'flexmode' will make the first 1gb of both sticks run on dual channel and the last gb will be left as single channel.

True dual channel will give you a peak bandwidth of 10.6gb/s
667mhz * 8bytes * 2 channels = 10.6gb/s

But in the end its bottle necked by your CPU's fsb at 6.4gb/s. It cant communicate fast enough.
(200mhz FSB x Quad pumped x 8bytes/64bits = 6.4gb/s)

 

Uh... In this setup, 2 gb is running in dual-channel and 1 gb is running in single-channel.

In this setup, all 4 gb will be running in symmetric dual-channel, but if you use a 32-bit OS you'll only be able to make use of like 3.2-3.5 gb or so. But it'll all be dual-channel.

 

Yeah, 2GB, my bad. The fact is, if you have 2x2GB sticks, you will have better performance than you would with 3GB. Though performance is "minimal", obviously youd have to be the one to judge whether its good or not. If you want the BEST. Get 4GB in there.

 

Ah, good to know. Thanks for the replies!

My laptop is on hold while it waits for a backlit keyboard, so I am going to change it. Maybe the processor too.

 

I should point out that of all the things that "feel" the fastest when it comes to upgrading computers, memory speed is currently not king. In fact, you tend to hardly notice it at all.

The motherboards and storage devices themselves still tend to provide the bigger bottlenecks. If data access was ramping up like graphics and processing then all of us would probably feel like we could warp dimensions with our dells.

Point is, get whatever RAM you think you need. Don't let the techie stuff persuade you too much.

 

Intel calls it flex mode.
http://www.intel.com/support/motherboards/desktop/sb/cs-011965.htm