Idiot's Guide to DDR-RAM

[alchemize]

Forgive me for posting this here, but it was here, Motherboards, or Peripherals Figured the OC'er forum is the better one since most people who OC are concerned about their RAM (specifically DD-RAM, since it is the most popular).

I'd like some help in putting together a brief little guide to RAM for posting in the endless RAM hot deals and question posts...

1) "Name Brand" versus "Generic", RAM manufacturers (Micron, Samsung, Hitachi, Hyundai...the big 4, who else?), "Assemblers vs. Manufactuerers"
2) Heatspreaders (marketing gimmick or helpful? Rebranding)
3) "Name Brand" versus "Generic" PCB's. 4 Layer versus 6 Layer.
4) CAS and CL, timings, Voltage, NS (6 versus 5.5 versus 4.5 etc.)
5) 32x8 vs. 64x4
6) JDEC Standards through PC3200, what is PC3X00?
7) Buffer, Error Checking, Registered
8) What Else?


Anyone care to help me collaborate on this? Short, sweet, idiots guide!

P.S. I don't claim to be any kind of expert on this, just smart enough to break things

 

[alchemize]

Not one single vounteer?? :Q

 

[DAPUNISHER]

I submit that you're wasting your time creating a n00b guide to memory, why? because the vast majority of n00b questions concerning memory are answered in the Crucial FAQs database just a few examples

Description:

Is all memory created equal? What are the differences?



Solution:

No, all memory is not created equal. Think about it, there are many fast food chains that sell cheeseburgers. Even though it's just a cheeseburger, everyone makes it a little differently.

Manufacturing DRAM is similar. An 8Mb x 8 chip from Micron or any other DRAM manufacturer will give you the same amount of memory, but each manufacturer's parts will have slight differences in some critical parameters. In other words, there are differences between "identical" DRAMs.

The most quality-conscious chip manufacturers, like Micron, will put every single chip through an extensive series of tests rather than just checking a sample of parts. They will test chips under normal operating conditions as well as under varying voltages, temperatures, and other "stressful" conditions.

Chips also go through a burn-in process at elevated temperatures to help identify any borderline parts. This process accelerates failure normally seen as "infant mortality." Chips that would fail early during actual usage will fail during burn-in. Chips that pass have a life expectancy much greater than that required for normal usage. Burn-in further helps to prevent failures from reaching you, the end user.

For more information about quality memory and the potential risks of "bad" memory, click here.

Description:

How do I know if I need parity, non-parity, or ECC memory?



Solution:

The general rule of thumb in deciding what type of memory you need is to look at what's already installed in your system. To find out if you have ECC, parity, or non-parity memory, count the number of chips on the module. If you can evenly divide the number of chips by three or five, the module is ECC or parity, if not, then it is a non-parity module.

So what if your system does have ECC or parity memory (the chips are evenly divisible by three), how do you know which one you have? One way is to look at the part numbers on the chips of your module. If each chip has the same part number, you have ECC. If one chip is different, you have parity. An even easier way is use the Crucial Memory Selector¿. Just select your system make and model and our Memory Selector will tell you which type of memory works in your system.

If you are building a PC and deciding which type to use, the following guidelines should help. If you plan to use your system as a server or a similar mission critical type machine, it is to your advantage to use ECC. If you plan to use your PC for regular home, office, or gaming applications, you are better off with non-parity.

Using ECC decreases your PC's performance by about 2%. Current technology DRAM is very stable and memory errors are rare, so unless you have a need for ECC, you are better served with non-parity SDRAM.

Description:

Can I use memory with ECC on a board that does not support ECC?


Solution:

Most motherboards that do not have an ECC function within the BIOS are still able to use a module with ECC, but the module will run in non-ECC mode. Keep in mind, there are some cases where the motherboard will not accept an ECC module, depending on the BIOS programming. The only sure-fire way to test this is to place the module in the motherboard and see if the BIOS will recognize the memory addition.

Description:

What do 16x64, 16x72, etc. represent when describing memory, and how do they affect what I should buy?



Solution:

If you are shopping through Crucial's advanced search or are shopping by motherboard, you may see the size of your module written in the format 16Meg x 64, 16Meg x 72, etc. In this format, the second number gives the width of the data path in bits. If this number is divisible by nine, it is a parity or ECC module; otherwise, it is a non-parity module.


You can determine the size of your module from this format by multiplying the two numbers together, then dividing by eight or nine, whichever results in an even number. This gives you the size of your module in megabytes (MB).

The list goes on and on, and everything you've listed is covered excluding the data cocerning memory rated@speeds beyond 3200DDR. My suggestion to you is to point them to the Crucial FAQs for 99% of the questions they have and save yourself the headache and trouble of attempting to compile a guide that will address every n00b question Of course do as you will but understand that your only reward will be the satisfaction you derive from your efforts and that a great deal of the work you do will be redundant and the n00bs ability to continue to ask the same questions over and over and over will exceed your ability and/or desire to continue linking them to your guide. For example, look at Andy's FAQs, no matter how many times he or one of the members points n00bs to it or the facts that it has it's own link on the front page and is at the header for almost every forum, the n00bs just post their questions because it's easier to have the info spoon fed to them than have to do their own research I.E. reading

This concludes my rather lengthy opinion on why your brain child is an effort in futility Good luck if you still intend to undertake it and I'd enjoy being proven wrong about this

 

[alchemize]

DaPunisher,

I guess I was thinking of something a little different. Crucial does provide a great FAQ, delving into a technical level of detail that is beyond what I was thinking. I'm thinking the (Anandtech Forum Generally Accepted Beliefs) Idiot's Guide to DDR-RAM!, AKA the AFGABIG (please dont rearrange the letters)

I.E. :

2) Heatspreaders (marketing gimmick or helpful? Rebranding)
"Heatspreaders are generally accepted to not make a difference in system stability. Their primary use is for the reseller to 1) "add value" to the RAM 2) Cover up the RAM information! (Oh, and if you take the heatspreader off, you void the warranty!!)

6) JDEC Standards through PC3200, what is PC3X00?
"There is no such thing as PC3X00 beyond 3200. PCXXXX is a manufacturing standard. Any place that claims that, is claiming they have overclocked some unknown chip to that speed."

 

[DAPUNISHER]

It's an admirable undertaking and I wish you the best of luck with it I'm disenchanted with the concept due to my observation of how frequently Andy's goes unperused and the fustration I've seen him exhibit, it's rare for him to get that way, but it has happened. Anywho, just providing you with some feedback on your project, and I do appologize that it's not very positive but it's how I feel BTW, it's JEDEC

 

[SinfulWeeper]

Well I never had a CPU that got passed 144FSB but I know my XMS3000 memory is upto the future busses thanks to THUGSROOK's postings.

Here is my take on the heat spreaders (others may disagree though). @ 144FSB CAS 2-2-2-5, 3:4 memory ratio. The memory gets rather hot to the touch with or without a heat spreader. So the idea is good, but the excecution lacks.
My plan to fight the heat was simple. I removed the heat spreader and very carefully applied AS3 to the chips making sure not to get any on the pins. I then put a thermaltake active memory cooler with heatsinks on them, and that got rid of a good chunk of heat. I would loan my memory to Thugs if I had more DDR memory to play around with, but it is my only stick .
I am sure higher FSB are possible now. But I have no way to find out. In either case I think the heat spreaders are a waste of time.

CAS setting help a lot in benchmark apps. But real world programs generally do not take advantage of CAS settings. To name one that does care though is SETI. I am sure there are many others though. I just do not deal with them.

From what I gather, PCB layering is very imporatant for performance. But I can not vouch for reliability. I had some pretty good chips on bad PCB that still work @ rather slow speeds. On the other hand I had the same chips on good PCB that did not last longer than me sitting on the thrown. But generally speaking. You can not go wrong with name brand. Personally I like Corsair. I hate Crucial/Micron. I have not tried Samsung yet, but everybody seems to rave about them.

JDEC standards are generic based on CPU FSB support I think... Example. There is PC2400, my PC3000, PC3500, and PC3700. Those are not official standards. They are as follows. PC1600, PC2100, PC2700, and PC3200. Manufactures just generalize the PC rating based on what the memory may do.... but I dont know if that is correct. Maybe somebody will enlighten us.

ECC, you dont need it unless you run servers. Registered is generally another term for it. I am not sure about the buffer though.

The rest of your questions I do not know.

 

[cowdog]

Hey, I think it is a great idea. I can help by being the dummy...

dapunisher, there are nearly infinite resources out there for most topics, but finding them isn't always a cake walk, and that information isn't always in a format that sinks in for everyone. For example, I've never heard of the Crutial FAQ before. If you wanted to buy new telemark skis or pick the best ice axe or learn more about NMS (an ordination technique) or find out how much money is spent in your state with the National Fire Plan, it's all there. But it may not be all that easy to 1) find good information or 2) find it in a format that works (we all learn differently). And I may be an OCing noob, but I'm no dummy. I always appreciate additional information resources. What I don't understand is the 'tude about noobs and noob questions. In my professional life, I have found that the best way to further my own learning is to teach or help solve problems. I don't view my own learning as a waste of time. I don't mean to be disrespectful or pick a fight. I simply wanted to point our an alternative perspective.

 

[SinfulWeeper]

well said

 

[DAPUNISHER]

You've misunderstood my perspective I can not state it any plainer than I already have, it's not the effort to educate or the method I'm disenchanted with, it's the hordes of people who do not do the reading and research you obviously undertake to find the necessary info. The AT FAQs that are posted at the top of almost every forum go utterly unread and ignored while the same question that's been asked literally hundreds of times!!! is asked in the forums over and over and over! I don't believe any guide will disspell the incessant barrage of the same questions being asked. It's not a matter of how they best assimilate the information, it's a matter of laziness, lack of will to find the answer, and the reliance on those who've done the research to spoon feed them the answers! Read my previous posts again if you will, do I display an attitude or do I factually state what I've observed here? Andy has compiled the FAQs because these questions are asked continously, and at the top of the forums it states "Before you post, please read the AnandTech FAQs for answers to commonly asked hardware and software questions." but are they read? No! and then they ask the question in the forum anyways To summarize, I've wished him luck and hoped that he succeeds where others have failed, but my life's experience in this area has been that for every person who really wants to know there are 50 people who just want the "quick fix" answer handed to them so they can obtain the instant gratification they seek.

And just a word of self defense, take a look around and see how often I attempt to help people before asserting I have an attitude about helping others. I spend more time trying to be helpful than 90% of the members of AT which number over 100,000 Also, search to see how many flame wars I've been in, good luck, you won't have much success I've provided what I feel to be invaluable feedback for his edification, and I submit you are being a little overly sensitive (just as I am right now) by taking offense to the n00b statements

Best of luck once again alchemize, I hope your endeavor bears fruit where others have not

 

[cowdog]

OK, OK, good points. I was reading your first post with a little too much apres chili sensitivity. Hehe.

Peace, cowdog.

 

[Zap]

Perhaps, instead of just a link to the whole FAQ page at the top, a list of links can be provided to the individual FAQs that best match a particular forum.