What does ALL this RAM stuff mean?

[[Dr. V]]

This is has been a long time question and confusion among many people. Although a lot of us may know what changing different parts of RAM does, a lot of us may not know exactly how and why it changes. In this article, you'll learn about RAM in that way you never wanted to - but it won't be annoying - I promise.

I. SD, RD, DDR-what now?

Yes, there are a helluva lot of markings that come along with RAM. First of all you need to know the TYPE of RAM you're working with. Types of RAM go back to the beginning of computers and all depend on what your motherboard can accept. SDRAM is really the furthest back we'll go in terms of being readily available and customizable in systems (on a large scale). For availability, the first motherboards that supported SDRAM were on shelves in 1993. After RD RAM came RDRAM - definitely a BIG jump in oveall performance, price (/value), and overall value. You could have higher capacity modules, and much faster performing parts. RDRAM boards were available in 1996.

Image i - SDRAM:


SDRAM is comprised of 184 pins, which slip into 184 contact pins in the RAM slot of a motherboard.

Image ii - RDRAM:


RDRAM came in 168, 184, or 242 pin varieties - all for different implementations.

NEXT: DDR. After SD RAM deserves a new paragraph. DDR could be called the largest performance increase from one RAM architecture to another. From RDRAM to DDR RAM - the difference was HUGE and VERY noticeable. DDR RAM was much, much faster, ran much more efficiently, and quickly became much more popular than SDRAM/RDRAM ever was/could be.

Image iii - DDR RAM:


Again with 184 pins, and again with a new arrangement.

Not too soon after DDR, came DDR2 (wow, innovative name - wait 'til you hear the next one). DDR2 is what's considered currently the mainstream type of RAM. Every recent board and ones that are still being released are DDR2 boards. DDR2 wasn't as big of a jump as DDR was from SD RAM, but it was still most definitely a performance increase. Basically what happens with every new release is that the newer RAM has the ability to run a lot FASTER than it's predecessor which, at this point with every architecture back to SD RAM could already have 2-4 GB if people wanted, is the most important thing. DDR2 pushed voltages and timings as far as possible to get insanely high clocks and much better performance than we could ever dream about with DDR.

Image iv - DDR2 RAM:


FINALLY - 240 pins this time! A whole new architecture with more pins and a different (but similar looking) arrangement than DDR.

DDR3 (again with the innovative names) - truly the speed DEMON of all RAM. Generally, RAM voltages are a big concern. DDR3 has that covered. DDR3 safely, and very efficiently is available and the most disgustingly high speeds RAM has ever begun to think of dreaming about. With speeds pushing 1866MHz and beyond, DDR3 RAM is able to run at voltages around and even under 2.0v - this is wild. DDR3 isn't as refined or mainstream as any other RAM yet, so it's hard to really say much about it unless we look at the very few reviews floating around - but even then, DDR3 isn't even in its final form yet.

Image v - DDR3 RAM:


Same pins, same arrangement as DDR2 - but VERY different. Also, you can't stick DDR3 RAM in a DDR2 RAM slot - most definitely not.

STOCK SPEED BREAKDOWNS FOR DDR, DDR2, AND DDR3 RAM:

DDR: 266MHz (PC2100), 333MHz (PC2700), and 400MHz (PC3200).
DDR2: 533MHz (PC2-4200), 667MHz (PC2-5300), 800MHz (PC2-6400), and 1066MHz (PC2-8500).
DDR3 (what's available right now): 1066MHz (PC3-8500),
1333MHz (PC3-10666), 1600MHz (PC3-128000), 1800MHz (PC3-14400), and 1866MHz (PC3-14900).

Now that you know the order of RAM and what it's all about, let's take a look at a breakdown in a timeline:



OK...that's all well and good...but what does it all mean? What do these MHz ratings mean?

II. Understanding Speed and Capacity of RAM

There is the section we need next. Now, there are many things that affect overall performance of ram. CAPACITY (MB - megabytes or GB - gigabytes), FREQUENCY (MHz - megahertz), and CAS LATENCEY (ms - milliseconds) are the important ones. Let's break it down like this for basics:

YOUR COMPUTER, AT ANY TIME, CAN ACCESS [CAPACITY] GIGABYTES OF RAM [FREQUENCY] TIMES IN [CAS LATENCEY] MILLISECONDS.

What does this mean? Let's say you had 4GB of RAM rated at 533MHz (this would be DDR2 RAM), with a CAS Latenecy rating of 4ms (definitely a low end "value" kit of RAM). This means your computer, at any time, has access to 4096MB of total RAM. Your computer can access this total amount RAM 533 times in a 4ms window of time.

Now let's say you have 4GB of RAM rated at 800MHz (DDR2 again), with a CAS Latenecy rating of 4ms as well (this is definitely a much higher end kit). This means your computer can access 4096MB of total RAM 800 times in 4ms rather than 533 times.

After reading this segment one, two, three or however many times you need to - you should understand how frequency and timings of RAM change the overall speed of it. Capacity means NOTHING when we're rating speed. Capacity comes in when we're talking about how much total RAM your computer has access to.

III. Recommendations

There are many categories of recommendations for RAM: which speed, which timings, which company....and we'll cover them now.

Generally, the higher the speed the better the RAM. But this definitely doesn't meen just the frequency of the RAM. This is why, if you're building a more than basic system, you should stick to reputable companies and their mid-higher end offerings. The lower the timings, the better - the higher the frequency, the better - these two go hand-in-hand. So what's the perfect compromise? Generally speaking, 800MHz of DDR2 RAM @ 4ms or 1066MHz of DDR2 @ 5ms is the answer. The two ratings I just gave you is standard for high end offerings. I have a Crucial Ballistix set of RAM that runs at 4 CAS when it's 800MHz, and 5 CAS when it's 1066MHz (which is what I'm running it at now) with no voltage changes.

So, now with the falling prices of RAM all around for the introduction of DDR3 coming soon, here are the recommendations:

800MHz RAM @ 4ms CAS, or 1066MHz RAM @ 5ms CAS.
Companies: Corsair, OCZ, Crucial, Buffalo Firestix, Super Talent, G.Skill, Patriot (pretty good RAM although quite overpriced) - and that's about it. There are other offerings that have solid RAM at the lower level, but these companies offer a wide range of RAM be it low to extremely high end.

I hope in reading this article you have a better understanding of RAM altogether. It's nothing utterly and horribly complicated once you grasp the jist of it, and it's always good to expand your hardware knowledge. Feel free to contact me with any comments/questions either here, in a PM, or in an email.

-Jonathan Varcabet, the <BEAST>

[Yellowhello]

Great guide! I recommend you put some pics in there to break it up, I have trouble reading that big a block of text without pics. Maybe some links for the recommendations. Again, great guide.

[gvblake22]

I think you should add Mushkin and Kingston to the list of RAM manufacturers. Maybe also cover Registered/Unbuffered and ECC/Non-ECC RAM too?

Good little guide that coves a lot of the basics, thanks! :clap:

[Yellowhello]

Hmm, maybe some time periods also.......... What year DDR came around, what year SDRAM came around, etc, etc.

[[Dr. V]]

Thanks guys.

I'll definitely make this guide a bit more comprehensive. Adding info about registered and unregistered, also recommendations are definitely on the top of my list.

In terms of time periods - great idea. So check back soon for a thread update. I'll probably get started tonight (or maybe in the next few minutes).

EDIT:

Also, I'm gonna mention some things about pins;)

[[Dr. V]]

A nice revamp to the thread. Some more info coming soon!

[Zambini]

Very sexy.

[Yellowhello]

Ah, much better! Lovin' the guide, ST!X!

[[Dr. V]]

Originally Posted by Zambini

Very sexy.

LoL dude that was awesome

Thank you BTW...

Originally Posted by yellowhello

Ah, much better! Lovin' the guide, ST!X!

Much appreciated sir

[halutzparilla]

St!X i must say well done...

+1 i will appreciate if its on timeline graph and more pix ...