Why is it not possible to get 3GB sticks?

[cppmonkey]

I have been asking myself for quite sometime as to why memory stick manufacture don't produce 3GB sticks.

Pros
Suitable for skt1336 with Dual Channel board and well as AMD systems
Cheaper to produce than 4GB sticks
6GB kit cheaper than 8GB kits with out
More worth while then 4GB on 64bit due to system overheads
Option for 9GB kits

Cons
Possible compatibility issues
Cannibals 4GB stick sales

If it possible to have triple channel memory interfaces and triple core cpus (yes I know they aren't natively) why not 3072MB memory sticks?

[TAKTAK]

Binary

1,2,4,8,16,32,64,128,256,512,1024,2048,4096,...~...

you could do it, but, it would be financially preventative compared to 4GB etc

[arthurleung]

Can they even stack chips on DDR3?

I don't really see how to get 3GB DDR3 unless using 24 chips, or mix 1Gbit and 2Gbit chips, which I think would be equivalent in performance to running 2GB,1GB,2GB,1GB sticks in asymmetric dual channel? Assuming both sides of ram are accessed concurrently (could someone proof me wrong?)

Which really doesn't worth making.

[kalniel]

, which I think would be equivalent in performance to running 2GB,1GB,2GB,1GB sticks in asymmetric dual channel? Assuming both sides of ram are accessed concurrently (could someone proof me wrong?)

I run 3076mb in dual channel no problem - 2x1gb and 2x512mb, so each channel has 1x1gb and 1x512mb. There's no performance hit. You could do the same with densities of chips on the DIMMs, however there's simply not enough market differentiation - if you're going for more than 2gb then you might as well get 4gb.

[arthurleung]

I run 3076mb in dual channel no problem - 2x1gb and 2x512mb, so each channel has 1x1gb and 1x512mb. There's no performance hit. You could do the same with densities of chips on the DIMMs, however there's simply not enough market differentiation - if you're going for more than 2gb then you might as well get 4gb.

I mean if the controller access both ranks of a DIMM in parallel, then it would be:

Say 4 DIMMs (A,B,C,D) with 2 Ranks (1,2)
A1 A2 B1 B2 C1 C2 D1 D2

In your case (2x1GB+2x512MB)
A1 A2 C1 C2 are 512MB each
B1 B2 D1 D2 are 256MB each

A1+C1 = A2+C2 = B1+D1 = B2+D2 = 768MB -> Symmetric Dual Channel

In the 3GB stick case (1 Rank high density, another rank low density, or 1 Rank with 8 chips and another rank 4 chips)
A1 = C1 = 2GB
A2 = C2 = 1GB
A1 + C1 = 4GB , A2 + C2 = 2GB -> Asymmetric Dual Channel

I'm not a ram engineer, I could be all wrong

EDIT: I forgot I had some single sided ram lying around that ran in dual channel, so I'm definitely wrong.

[cppmonkey]

Not really talking about 3GB on its own, more as a theoretical 6GB kit (2x 3GB)
The 3GB could be archived with 12 chips rather than the 16 that would make up a 4GB stick.
It's meant as a potential cheaper alternative to 2x 4GB for people wanting to take full advantage of a 64 bit operating system, 4GB doesn't quiet do it justice.
6GB more room for Windows to prefetch booting application performance
Helps bridge the gap between cost and the performance increase at the end of it all

applications running on a 64 bit operating system use up to, something like 30% more memory then if they were run upon 32 bit. This is largely due to the 64 bit memory addresses within the application taking up, yea you guessed it twice as much memory.

A comparison of 64 bit vs 32 bit on an Athlon II, could throw out some unusually high margins whilst running Windows x64 due to the lack of available cache. Completely hypothetical really

[Meaker]

Not really talking about 3GB on its own, more as a theoretical 6GB kit (2x 3GB)
The 3GB could be archived with 12 chips rather than the 16 that would make up a 4GB stick.
It's meant as a potential cheaper alternative to 2x 4GB for people wanting to take full advantage of a 64 bit operating system, 4GB doesn't quiet do it justice.
6GB more room for Windows to prefetch booting application performance
Helps bridge the gap between cost and the performance increase at the end of it all

applications running on a 64 bit operating system use up to, something like 30% more memory then if they were run upon 32 bit. This is largely due to the 64 bit memory addresses within the application taking up, yea you guessed it twice as much memory.

A comparison of 64 bit vs 32 bit on an Athlon II, could throw out some unusually high margins whilst running Windows x64 due to the lack of available cache. Completely hypothetical really

All chips must have the same bit connection, there are many tricks used assuming the whole system is symetric.

There is no way to do this and create a 64bit stick that is 3GB.

Just like the Nvidia cards have strange memory configurations.

[singdollar]

I believe is the memory addressing issue. the memory location are always based on the power of 2. Therefore the memory location are always starting from 256, 512, 1024, 2048 and 4096. Therefore if you are designing 3GB memory, you are actually wasting 1024 memory location. As a result, the memory designer will fully utilize the memory location by coming out with a 4096 (4GB) memory stick. instead of 3GB one.

[floppybootstomp]

Same reason you can't put your elbow in your ear

[scaryjim]

Same reason you can't put your elbow in your ear

Because you'd electrocute yourself?!?!

[jim]

Because you'd electrocute yourself?!?!

Eh??

[floppybootstomp]

Because you'd electrocute yourself?!?!

Precisely.

scaryjim is a wise man.

[Zak33]

Precisely.

scaryjim is a wise man.

I once put my ebow in someone elses ear....

they didn't however ask for a 3gb stick of ram.. they seemed to want a fresh pint of beer and someone to wash their shirt