What's the Difference Between PC* and DDR* RAM Designations?

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Anchoret

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For example, isn't PC2700 the same thing as DDR333?

Why are there two naming systems?

Thanks for any clarification on this. I've always been confused about it.
 

Anchoret

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Rumpo-Stiltskin said:
Couple of articles for you...
Ah!

So...let me see if I understand this:

DDR333 is the designation for the individual chip and PC2700 is the designation for the complete memory module made up of DDR333 chips, right?
 
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Hi Rumpo-Stiltskin Check this out. I haven't run across anything that wikipedia doesn't address pretty thoroughly.

Raybro

EDIT... Boy did I mess that up. Not only did I address to to the wrong guy, but the guy I addressed it to had already made the same recommendation. Oh well, my bad.

Raybro
 

Anchoret

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raybro said:
EDIT... Boy did I mess that up. Not only did I address to to the wrong guy, but the guy I addressed it to had already made the same recommendation. Oh well, my bad.
Uh, well...anyhow...is my short-form explanation above correct? :confused:
 
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Anchoret said:
Ah!

So...let me see if I understand this:

DDR333 is the designation for the individual chip and PC2700 is the designation for the complete memory module made up of DDR333 chips, right?

Nope...... very wrong indeed. :D

The "PC" rating addresses bandwidth whereas the 333 for example is bus frequency.
Did you read them?
 

Anchoret

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Rumpo-Stiltskin said:
Nope...... very wrong indeed. :D

The "PC" rating addresses bandwidth whereas the 333 for example is bus frequency.
Did you read them?
Yes, twice, and as best I understand them (before my eyes glazed over in incomprehension), for practical purposes PC* (for whatever technical spec it is) refers to the spec of the module and DDR* to the spec of the individual chip:

JEDEC has set standards for speeds of DDR SDRAM, divided into two parts: The first specification is for memory chips and the second is for memory modules.

Chip specification

[...]
* DDR-333: DDR-SDRAM memory chips specified to operate at 166 MHz
[...]

Stick/module specification

[...]
* PC-2700: DDR-SDRAM memory module specified to operate at 166 MHz using DDR-333 chips, 2.667 GByte/s bandwidth
 

Triple6

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If you want the simple answer then they mean exactly the same thing.
 

Anchoret

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Triple6 said:
If you want the simple answer then they mean exactly the same thing.
Yes, that's what I meant to determine. While they are not the identical standards, PC* is a module spec and DDR* is a chip spec.

When momboard docs say it uses DDR333 memory, that's actually a misnomer, as it should properly say it uses PC2700 memory, as the end user doesn't typically build his own modules.

Right?

And so all this newbie confusion about whether to buy DDR333 or PC2700 is caused by some uninformed technical writer's poor grasp of JEDEC standards, and that DDR333 chips are always what's going to be in a PC2700 chip...right?

I'm just trying to get the paint out of the bucket and onto the wall here, folks.
 
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Well, the terms DDR333 and PC2700 are effectively inseparable if that's what you mean.
So in relation to naming, yes they are the same. :)
 

Triple6

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There are lots of terms that are mis-used in every industry, its just a fact of life. Many times professionals make up their own terms and then they get widely used.

Where DDR400 would be used instead of PC3200 is where the modules are used not as system memory, like video cards.
 
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