are ddr 400 ram and DDR SDram compatible 5

[BIGBL]

wht is the difference between ddr 400 ram a nd ddr sd ram and are they compatible

 

[paparazi]

DDR ram (Double Data Rate) common speeds (PC2100/PC2700/PC3200 that's DDR266/DDR333/DDR400) these all have a single keyway and is presently the most common memory type, NOTE* will be slowly phased out for DDR2 (already available and in use on the very latest generation of Intel P4 boards and soon to be AMD M2 platform)
SDram is an older memory type, has two keyways and was commonly available in three speeds (PC66/PC100 and PC133)
The two types are not compatible with eachother (differant keyway fitting) only memory speeds from each type are able to run together and then they have to be compatible with the CPU being used.
Several years ago during the transition between SDram and DDR there were several popular motherboards that had both slot types (DDR and SDram) but with all of these boards the user had to choose to use one or the other NOT BOTH.

Martin


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[kmcferrin]

The key part that you left out is that DDR RAM is actually DDR SDRAM. Regular SDRAM topped out at PC133 (operatingly synchronously with a 133 MHz FSB), and then they discovered that if they transmitted data on the rising and falling edge of the clock signal they could double the effective data transfer rate, hence DDR memory. So DDR266 is really just 133 MHz SDRAM that is designed to transmit on both edges of the clock signal. It is still a form of Synrchonous DRAM (SDRAM) because it still operates in synch with the FSB (or memory bus) clock. The same is true of DDR333 and DDR400.

 

[cdogg]

BIGBL,

In your question, you mention DDR 400 and DDR SDRAM.

Well, DDR SDRAM is the full name. DDR is the short name. There's no difference between the two, except that one name is the shorthand of the other.


However, I'm assuming that you meant to ask about DDR SDRAM versus regular SDRAM. As Martin said, the two are not compatible. They are different technologies altogether. It's like comparing a Pentium to a Pentium II.

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Albert Einstein
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[paparazi]

Hmmm, now you have me thinking guys, maybe BIGBL is refering to the different ways some sellers refer to the same thing.
As cdogg says PC3200 DDR SDRAM is the same as DDR3200 DDR which is of course DDR400.

But PC133 SDram is as described, a differant beast.

Martin

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[cupid11213]

i have a similar question at hand, i opened up my friends computer yesterday since he wanted to install a 256 RAM on his computer that a friend is giving him, when i opened up the pc and took out the ram (it did not say on there what kind of ram it was) it just said this; 9905006-022-a00-851715 the cpu is an Athlon (AMD) there was a chip on the center though that did say (dc/DDR266)

now the question at hand is this, will the ram his friend gave him be compatible?

since he said it was (DDR RAM) and what kind of Ram does his computer currently have?

thanks in advance guys i really appreciate it!

Some people make things happen, some people watch things happen, while others wonder what happened.

 

[Wishdiak]

cupid11213,

The most reliable way to check compatibility is to find the manufacturer and model numberr of the motherboard and go from there.

I've had a few boards that had been passed around that I could only identify by the Northbridge, but even that should help you to tell if the board is compatible with a certain speed of RAM.

Wishdiak
A+, Network+, Security+, MCSA: Security 2003

http://www.wishdiak.com

 

[paparazi]

cupid11213
As this centre module says DDR266 it's pretty safe to say he currently has PC2100 (DDR266) installed.
This means any DDR module will fit so you can try this module without fear of harming the motherboard.
Obviously it's best this module is either PC2100 or PC2700 (DDR266/333) as some earlier DDR motherboards have issues with later PC3200 DDR400 ram but as I say, it won't hurt to install and try.
Martin

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[rvnguy]

One could also look up a diag of the key slot as they are different and readily dicernable against a picture.

Or if in doubt, & you have nerves of steel:
you could try counting pins

SD RAM =168 pins

DDR RAM = 184 pins

rvnguy
"I know everything..I just can't remember it all

 

[cdogg]

For pictures:

http://www.kingston.com/newtech/rimmvs.asp

http://www.memorycity.com/shop/memory_basics.html

So keep in mind that SDRAM has two notches and DDR SDRAM has only one, in addition to the other descriptions listed in this thread.

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Albert Einstein
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[cupid11213]

thanks guys for all the help.

one more thing can a pc2100 have an (AMD) athlon cpu that the speed is around 800 mhz or somewhere around there? or is there more of a possibility that it is a pc100 or pc133

(the ram does have just one notch)


thanks in advance.

Some people make things happen, some people watch things happen, while others wonder what happened.

 

[paparazi]

Well this is most likely a SLOT "A" cartridge style Athlon 800 (if you are sure it's an Athlon and not a Duron)
As such it has a 200 front side bus and almost definately uses the earlier PC100/133 ram and not DDR.
Like this one?

http://techreport.com/reviews/1999q4/athlon800/athlon800-1.x

Martin





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[cyberspace]

If you are in doubt about the type & speed of your RAM - use CPU-Z available here -

http://www.cpuid.com/cpuz.php

Direct download link:

http://www.cpuid.com/download/cpu-z-132.zip

saves taking the machine to bits and then researching to see what RAM you have

Came in very useful many times for me.

'When all else fails.......read the manual'

 

[paparazi]

cyberspace
I'm sure CPU-Z is a really useful program but would you honestly go out and spend money on ram on the basis of what a software program is telling you?

I wouldn't consider slipping the side off a PC and writing down system information "taking the machine to bits" this program might be useful when used in conjunction with a visual inspection but not safe enough on it's own.

If you find PC100 installed I will give you this word of caution.
Newer PC133 modules can sometimes have issues (either not seen or reported as half the capacity) with older motherboards, so either buy 2nd user of known vintage or stick to PC100.
Online vendor "Crucial" also garantee compatibility.

Martin






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[cyberspace]

My point is that not everybody can just slip the side off a pc and determine from that brief inspection the exact type and speed of RAM in the machine.

Have you even used CPU -Z? I assume not from your comment.... It's always reccommended in other technical forums, and I personally use it alot and have never ever had any issues as a result and it's never given me duff information. If serious overclockers swear by it then I think it's able to tell you wether you have DDR SDRAM or just SDRAM....

The Crucial Advisor is also very good but again not everybody knows the exact model of their PC so getting the right info is not always straight forward.



'When all else fails.......read the manual'

 

[cdogg]

cyberspace,

You do have a good point about the usefullness of CPU-Z.

I think the point Martin was trying to make is that the best option (if it IS an option) is to check the specifications of the motherboard. Doing so can lead you to the manufacturer's website finding strange and unusual recommendations for memory, PCI slot configurations, BIOS updates, etc.

It sounds like a chore for just a memory upgrade, and usually you'd be right making that comment. However, consider this. I've come across several motherboard models that required you to use a specific type of memory (terms like x8, x16, single rank, double rank, etc). In situations like that, you have to know what kind you have so that you can properly fill the DDR DIMM slots with the right combinations. The "kicker" is that software apps like CPU-Z or Everest Home Edition (ones I typically recommend using) will not show you. Only physical inspection of the memory module and googe searching part numbers will tell you this.

Situations like that are rare though, and for the most part, software applications are reliable enough. It never hurts though to go the extra mile...

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Albert Einstein
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[paparazi]

cyberspace
Nope, I've not used CPU-Z, mainly because Sisoftsandra has always worked very well for me.
OK! I guess I was just playing it safe by suggesting that cupid11213 uses both methods.
Surely better to be safe than sorry.
Also as this site is solely for the use of computer professionals it is generally accepted that all members possess a certain degree of competence, removing two screws and a case panel therefore shouldn't be too much of a problem.
Martin







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[cupid11213]

thanks for all the help guys.

I am still wondering if a pc100 or pc133, can have a centre module that says "DDR266" since I only work mostly with ISP issues i have not come accross issues like this before (since most of the time all you have to do is remove the RAM and read off of it what type it is.)


paparazi I did see at start up that it said cpu Athlon (AMD) on there and something like 800 or so mhz. that is why i was curious as if an pc 100 or 133 can have a DDR266 centre module.

thanks guys,

Some people make things happen, some people watch things happen, while others wonder what happened.

 

[paparazi]

cupid11213
It's hard to follow exactly what questions were relating to which machine.
You started the reply by saying " I have a similar question to hand, I opened up my freinds computer etc"
I had assumed you were talking about two differant computers and not the same one, you weren't all that clear in your questioning.
As I said in the first post I replied to, if the center module already fitted says DDR266 then that is definately PC2100 (DDR266) identifies by a single keyway (notch) on the connection side of the module.
PC100/133 has two notches and is not interchangeable or compatible.
To save further confusion and to prevent me or others giving you incorrect information it would be best if you could just remove the side panel and tell us the make model and revision numbers screen printed on the motherboard, that way we will be able to tell you exactly the CPU type and memory required.
Martin

Martin

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[cupid11213]

you are right sorry about that paparazi.

yes i was speaking of the same machine. see the centre module says ddr266 [\b] but when i was looking at the computer start up it said cpu Athlon 800 mhz[\b]. so i was left wondering from the previous reply's that i got if a computer that has a ddr 266 centre module[\b] ( that we established was ddr) could actually be a pc100 or pc133 and not ddr [\b].

But from your last post your answering my question since the centre module says DDR266 AND THE CONNECTION SIDE ALSO ONLY HAS ONE (NOTCH). So i thank you very much for all of your time and thanks to all of the people who replied to my post.

Luis



Some people make things happen, some people watch things happen, while others wonder what happened.