DDR3 RAM Explained

Das Capitolin sends us to Benchmark Reviews for an in-depth feature on DDR3 memory that begins: "These are uncertain financial times we live in today, and the rise and fall of our economy has had [a] direct [effect] on consumer spending. It has already been one full year now that DDR3 has been patiently waiting for the enthusiast community to give it proper consideration, yet [its] success is still undermined by misconceptions and high price. Benchmark Reviews has been testing DDR3 more actively than anyone. ... Sadly, it might take an article like this to open the eyes of my fellow hardware enthusiast[s] and overclocker[s], because it seems like DDR3 is the technology nobody wants [badly] enough to learn about. Pity, because overclocking is what it's all about."

Just a tad over the top?

This article was rather amusing, at times I wasn't quite sure if the author was serious, with statements like:

One particularly important new change introduced with DDR3 is in the improved prefetch buffer: up from DDR2's four bits to an astounding eight bits per cycle.

Woo I think I wet my pants there. But the author seems genuinely excited about this technology. I mean:

DDR3 is very similar to the advancement of jet propulsion over prop-style aircraft, and an entirely new dimension of possibility is made available.

Hahaha

Re:Just a tad over the top?

Whether or not the author was really serious, I think about the only really worthwhile comments of his might have been related to the "uncertain economy".

Right now, all too many people I know are finding themselves out of jobs, with no good-paying alternatives in sight. I just attended my girlfriend's college graduation ceremony yesterday afternoon, and the guy sitting behind us was a 40-something year old who decided to go back to school last semester, because he couldn't make it anymore in the construction business. He said he worked in construction for 18 years, and until 3 years ago, it was a good career for him. But in the last few years, things have gotten so bad, many people are resorting to selling off the trucks and equipment they used in their trade, just to keep the bills paid and to stay afloat. They're seeing their work dwindle to the point where they can do it as a side job, but can't guarantee they're always busy. Therefore, he finally decided to go back to school and start a new career path.

My g/f is in a similar dilemma. Here is she. fresh out of school with a degree in psychology, and really can't do a thing with it except continue on to earn a Masters' in psych. After that, she could open her own practice (MORE $'s on top of huge student loan debt!), or possibly partner with someone else - with results varying depending on what part of the country you decide to live in. She's thinking about going for a double major, with the 2nd. one in business .... because at least the internships for MBAs seem plentiful and promising right now.

Anyway ... my point is, most people just aren't going to be as "free" with their spending money as they were when they were sure their good-paying job was there for them. Playing with stuff like DDR3 vs. DDR2 amounts to "unnecessary entertainment" for the computer hobbyist, really. You can get a plenty fast PC running regular old DDR2 memory that will do whatever you need done. Buying into anything else, just for the sake of "overclocking" amounts to tinkering and computer hot-rodding for the fun of benchmarking and seeing how high a number you can get. It's not a practical activity when finances are uncertain or possibly very limited.

Re:Just a tad over the top?

The author of this article seems to think that since 1.5V is 17% less than 1.8, the power savings are 17%. Granted, the saving is more like 31% if the memory has the same resistance, since power usage is proportional to the square of the voltage, but it's not worth reading an article from someone who doesn't know such basic knowledge that is so relevant to the topic being written about.

Re:Just a tad over the top? No ECC = NO buy

I really like ECC memory. I've built a lot of machines here and there for various purposes and people and can safely say that ECC should be mandated. People oft talk of blue screens, panics, etc. A lot of these are due to bad memory. And these types of errors can often be hard to replicate. I believe EETimes had an article about how bad bad memory is.

Anyhow, I'm on a 975X chipset with 4GB of DDR2 800 MHZ unbuffered ECC memory machine now. Not a single unforced error since I bought this machine and assembled it December, 2006. Nothing. This unit is primarily a gaming rig, the 3DMark 2006 score is 11500 with an 8800GTX, all with ECC memory.

The most irritating thing for me is, looking at the great new CPUs available, is the utter lack of any unbuffered ECC memory in the DDR3 range. This to me is unacceptable. I refuse to compromise so I will wait. Intel has a motherboard featuring DDR2 800 fully buffered memory for the 'high end workstation' , D5400XS, this is $600+. Supermicro offers something similar.

The X38 does DDR2 ECC, and for whatever reason the X48 took that away. I don't get why Intel wants to deny us DDR3 unbuffered ECC? Its really a selling point, a very good thing. If you overclock, its nice to have because it can tell you the limits minus the guesswork, not that I would bother with OC personally.

Fundamentally, without ECC, do you even know if the memory works at all? My experience leads me to believe that without ECC present, the answer is no at all.

Re:Just a tad over the top? No ECC = NO buy

I run memtest for a minimum of 48 hours on any new system I build and have never had any problem with RAM that has passed that. This is the best I can do without the premium of paying for ECC capable motherboards and RAM.

How about a DDR2 versus DDR3 chart?

Great, now that I know how well certain DDR3 chips overclock, can I see how DDR3 compares to DDR2 in terms of raw performance and overclocking ability? I'm not an expert on how DDR2 works, so DDR3 could be better explained to me by showing me how it is better than DDR2.

Re:How about a DDR2 versus DDR3 chart?

I came here to say the same thing. The whole article can only be called a theoretical comparison between DDR2 & DDR3, as there is not a single benchmark that compares the two. Where is the latency, bandwidth, power consumption, etc charts for DDR2 & DDR3 when running at similar clock speeds? The author says that people are taking the latency increase too seriously, and that it doesn't come into play, but then under the "downside" discussion, they mention the latency. Also, when all the arguments they use preface concepts with "in theory" or "should" kinda makes you think they're just making this stuff up. I'm still waiting for an AM2+ chipset that will support DDR3, as the Phenoms (I think) have a memory controller that supports it. That should give the AMD chips a boost when compared to the current crop of Intel chips as the on-chip memory controller should allow for better usage of the RAM, but again, I'll wait until a benchmark confirms it. Intel motherboards, at least to me, seem to be 2-3x as costly as AMD varieties, and don't always offer the same BIOS flexibility. Not to mention the top-end Intel chips are 2x as much as the top-end AMD chips, and I still prefer AMD over Intel when building my own systems.

Using His Jet Analogy

He's like a jet engine supporter immediately after World War II:

"Jet engines are inherrently capable of much greater speeds than propeller engines!"

"OK, so show me one that goes much faster than the prop driven spitfire?"

"Well, uh, there's the Gloster Meteor!"

"It does about 500mph*, right? That's not bad compared to the Spitfire XIX's 460mph. But there are tons of Spitfires out there, available cheaply vs. paying several times the cost for the Meteor for about a 10% speed improvement." *note: F-3 variant, not the "overclocked" tweaked versions that set speed records.

"Well, but the point isn't that it's better today. It's a better technology! It'll be better in the future! Props will never go supersonic. Jets can potentially go several times supersonic."

"That is cool. Doesn't really help me today though, does it? I'm still paying several times the cost for a small improvement, today."

"Yeah, but if you don't buy jets now, how will their prices ever come down? How will we ever reach the heady perfection they're capable of?"

"Again, not helping me today, is it?"

"But! But! It's really cool!"

Yes, the technology shows promise. But its future promise with only small increases today doesn't justify its current high cost.

If more people bought it, the cost would come down over time and more investment would mean unlocking more of that promise. Which is great in the future but gives you very little today in exchange for that high cost.

The argument he seems to be making is that everyone should adopt it right now, not because it actually gets them much for their money but because their investment will enable him to buy even faster stuff for a lower price later.

Not really compelling.

not cost effective for the performance gain

DDR3 is still 5-10 times the cost of DDR2, and the performance gain is not big (maybe 10% at best) on overall system performance.

Re:not cost effective for the performance gain

Exactly. I'm not buying a product whose only real advantage comes when you void the warranty.

Re:not cost effective for the performance gain

And to take it even further, that's just the cost of memory. A quick NewEgg search for DDR3 motherboard came up with a whopping 10 boards. The cheapest are 150 for open box items. The typical price is over 300.

Re:not cost effective for the performance gain

Maybe DDR3 is the memory industries way of keeping people on 32-bit OS's interested in their product? Because you can't really use much more than 2GB in a 32 bit system, and that's selling for about $50 now for DDR2 (I paid over $300 a year and a half ago!).

If you want real performance improvement get a 64 bit OS and 8GB DDR2 instead of 2GB DDR3. It will probably cost less and you'll notice the performance improvement as fewer accesses to HD (given you're OS knows how to pre-fetch intelligently).

Memory Bandwidth...

Memory bandwidth is not problem right now. I/O is too slow. We need faster disks and LANs first.

Don't [you] just [love] these...

... really careless[ly] written submission[s] that the editors [have] to fix [up] before they can be [read] by us[?]

Teenage enthusiasm

It's always nice to see a tech writer full of teenage enthusiasm, but this article goes a little over the top.

It's supposed to be an article about a performance enhancement, and there's barely any performance values at all (except for the theoretical peak throughputs on page 3, and we know how much that means).

I think what the guy really wanted was to write about planes, not about computer hardware.

DDR3 simply picks up speed where DDR2 left off... which is as accurate as saying an airplane picks up where a kite left off.

DDR2 technology is no better prepared to reach higher speeds than a propeller airplane is capable of breaking the sound barrier;

DDR3 is very similar to the advancement of jet propulsion over prop-style aircraft,

No advantage to DDR3 (?)

I was asked to purchase 4 of the fastest desktop PC's I could find (just less than a year ago) for a contract placement; I ended up going with the QX6850 and for 3 machines DDR2-800, and with the extra money on the 4th machine, going with a capable motherboard and DDR3-1333; hoping for at least some speed difference.

First of all, as the technology was brand new at the time, the motherboard, although capable of 1333mhz ram, it only detected it as 1066 (we double checked they sold us the right stuff), so we manually set the RAM in the BIOS to run at 1333.

After all the setup, on otherwise almost identically configured machines, we found absolutely 0 performance gain on the DDR3 machine over the other 3 DDR2-800 machines. Although one might argue that our applications we were using to test were not so memory intensive, the fact is it was a computationally intensive task that regularly accessed about 200-300mb of data from ram. I would think that even if everything would be pre-fetched into the 8MB CPU cache before it was used, we should at least see some small difference.

In the end, it seems that we spent an extra $800 for no noticeable performance gain.

Re:No advantage to DDR3 (?)

Sorry, just wanted to append some details:

- We were using XP Pro x64 edition
- I believe there was 4GB RAM, possibly 8GB
- I tested exactly the same program that we wrote and compile with the same input data and timed it between the DDR2 and DDR3 machines.
- The processing took exactly the same number of seconds on both platforms. (Approx 20sec). Testing on older Xeon 3.6 gave me approx 50sec, and Pentium D-3.2 at 30 seconds.

What about the 4GB limit in Vista 32?

The problem with sales of DDR3 is probably down to the fact that most computers are being sold with versions of Vista 32. To really make a difference with faster SRAM would probably also mean having a larger amount of SRAM. But the problem is Vista 32 only addresses just under 4GB of SRAM. As many computers for the home market max out by being supplied with 4GB of SRAM as new, the computers are effectively un-upgradable unless a different operating system is used. This leaves an interesting situation:- 1. Run Vista 64 - but then a large portion of hardware and software will not work as you cannot sign unapproved drivers. 2. Run Linux 3. Buy a MAC And there is the problem, the alternatives to using DDR3 are in fact called using a different operating system and adding standard DDR2 memory, which is more cost effective that paying the extra for the DDR3 SRAM. The only area I could possibly see DDR3 technology in the commercial hardware is in cutting edge graphics cards, where performance is everything. Unfortunately, as Vista 32 is already at is technology limit and that many potential users of this technology will baulk at the price, I can see games console manufacturers adopting this technology before the general PC market.

Bending the facts, paid advertising?

This article seems to be paid advertising, with some bending of the facts.
And the fact is that the double prefetch buffer is the sole reason for the double bandwith and the double latency. As a matter of fact the speed of the individual memory chips on the ram module are the same as on ddr2 (see that table in the article, just divide the ddr3 clock by 2 to get the corresponding ddr2 speed) - but instead of reading 1 bit from 4 chips at once into the prefetch buffer (that is four bit prefetch buffer), they are reading from eight at once (so that's the 8 bit prefetch buffer), so double the amount of data can be read in the same time (hence the double bandwidth). However because the memory chips are the same speed as in ddr2, the time needed to program the individual chips stays the same - so because the clock is double the speed, it takes twice as many clocks to tell the individual chips which bit we want to fetch. And that bullshit about lower latencies is also not quite right: ddr3-1600 cl6 is the same latency as ddr2-800 cl3 - and such modules have been sold for years.

Of course ddr3 is better, because it has higher bandwidth, and absolute latency is not worse than ddr2's. Also there are in deed technological advances (e.g. the lower voltage). But this article is still not exactly honest.

We Drink Ritalin

Tell me when DDR5 is ready.

Wikipedia says DDR5 was ready on 2001-03-27 [wikipedia.org].

Re:

I'm very curious about your sig:

> If PC gaming is dying, HTPC gaming can revive it.

Considering the HTPC itself doesn't seem to be gaining much traction these past couple years, and consoles have been encroaching (albeit very slowly) on the HTPC space, I

Re:

Because some value stability over speed.

Re:Not Needed

Hard disk speed, until SSDs become very common this is one of the causes of decreased speed because a HD can only run so fast

And the actual reason memory manufacturers have such a hard time selling memory performance is an extension of this; most purchases of memory have an implicit tradeoff: amount versus speed.

In most cases the real memory pain will come when you hit swap. That means you will almost always notice having less memory more than you'll notice having slower memory. So basically the only ones who end up having 'fast memory' on their system purchase checklist is those for whom money isn't an issue at all (ie, there is nothing else you could buy for that money that would improve your system (or life) more than faster memory). Or those who have very small applications they need to execute blazingly fast. Such as benchmarks.

Until those problems get fixed, faster RAM won't make a bit of difference to the end-user.

More accurately, faster RAM will make less of a difference than more RAM.

Re:

Hardware hack, smart guy.

I think I'm being trolled.

Re:stupid

Vista has sold 140,000,000 copies. Not what I would call a failure.

I wouldn't call it a success, either. I'd wager that figure is 90%+ copies that came with new PCs. The large majority of which probably end up in a corporate setting where it was re-imaged with XP Pro (happens all the time where I work and for our clients).