An Overview of Quad Band Memory

tedgyz writes "AnandTech has a short article on a new memory technology from Via, called Quad Band Memory (QBM). Rather than using dual-channel DDR to increase bandwidth, they use phase-shifting inside the memory modules to accomplish the same goal. The end result is simpler (and presumably cheaper) motherboard designs that are backwards compatible with current DDR modules. The downside? It is currently only going to available in a P4 chipset that Intel has not authorized."

Comments

Uhhh...

[GreyWolf3000]

The downside? It is currently only going to available in a P4 chipset that Intel has not authorized."

Keyword: currently. I'm sure the technology will be available soon for plenty of other motherboards. I don't consider this much of a downside (feel free to set me straight if I'm wrong).

It's Kentron's invention

[HardCase]

You can see more about this on Kentron's web site. They developed the technology, then released it, royalty free, to manufacturers.

Given the memory manufacturers' resistance to DDR400 and the achingly slow progress that DDR2 is taking (the module standard isn't even final yet), this technology has a pretty good potential to reach production.

-h-

I dunno, these are gonna cost more.

[io333]

From the article:

*snip*

Here's where the difference between QBM and conventional modules comes into play; QBM modules will have a set of 8 registers (QBM-10) as well as a phase-locked loop (PLL). The purpose of the PLL is to take the incoming clock signal from the chipset and shift it by 90 degrees; this shifted signal is then fed to the second bank of the DIMM, while the first bank receives the unaltered clock directly from the chipset.

The 8 registers then switch between which bank gets to transfer data every clock; because of the 90 degree phase shift, there is a slight delay in transferring data from the second bank but both transfers actually end up happening within a single clock cycle. The end result is that you get two DDR transfers per clock, or 4 bits of data are sampled per clock thus doubling the throughput of DDR (hence the name Quad Band Memory).

*snip*

QBM modules will obviously be more expensive than regular DDR modules, the question of how much remains to be answered however.

Let's see, one PLL... damn, I don't know if I can afford the extra six cents!

(That extra six cents though doesn't detract from fact that this idea is just pure genius... with about 30,000 folks slapping their forheads for not thinking of it first!)

Re:I dunno, these are gonna cost more.

[ZeLonewolf]

Let's see, one PLL... damn, I don't know if I can afford the extra six cents!

Well, actually, it won't be that cheap. When I was in college working on my senior thesis (Fall 2001), we had an application where we needed to use a PLL in a 2.4GHz transmitter circuit. The thing was approximately 1cm x 2cm x 0.5cm, and cost around $25, and it was damn hard to find. Now, that piece would obviously be far too large and noisy for use on a memory chip (but maybe not)... but the point remains, a PLL that needs to operate in the 100's of megahertz to gigahertz range AND be electrically quiet enough would, I'm sure, jack up the price more than marginally. Now, that $25 piece is all well and good for some flakey-ass collegetransmitter, but this chip is gonna need something that's low-noise, high-gain, and a bunch of other characteristics that WILL make it much more expensive.

Of course, you also gotta take into account that the PLL will (most likely) be hybridized (i.e. wafer removed and built custom onto the chip) and mass-produced, both of which will tend to drive the price down

On the flip side, though, we've become used to buying $20 sticks of RAM, so it might seem pricey at first :-)

FAQ about QBM

[kyoko21]

This is a link to kentron's FAQ about Quad Band Memory.

why is that a downside?

[geekd]

The downside? It is currently only going to available in a P4 chipset that Intel has not authorized."

Why is this a downside? Why should I give a rat's ass what Intel "authorizes".

Intel sure as hell didn't authorize my Athlon on it's Abit mobo with a Via chipset.

Is there an actual downside to not getting Intel's blessing (downside for consumers, not the company making the mobo)?

Re:why is that a downside?

[mabinogi]

The downside is that since VIA don't make motherboards, they rely on mobo manufacturers, and the mobo makers don't want to piss off Intel, and so aren't too quick to look at using unauthorized chipsets.

If no one makes the boards, the chipset may end up more or less stillborn.

If VIA had started with an Athlon chipset, or didn't have this disagreement with Intel over whether or not they're allowed to make P4 chipsets, then there wouldn't be that problem.

However, I would assume that there are obviously some manufacturers making VIA boards, so I would assume those ones would be the ones that would start making boards using this technology.

Re:why is that a downside?

[BaldingByMicrosoft]

VIA -does- make motherboards:

http://www.viavpsd.com/ ...but they're not exactly considered a 'tier-one' provider.

Re:But memory isn't the bottleneck anymore, is it?

[be-fan]

Um, disk isn't a bottleneck on my system. I do lots of C++ programming, and everything gets cached in RAM after the first build. Thus, my bottleneck becomes gcc ...err... CPU and memory bandwidth :) Same thing when I'm doing 3D rendering (which had better fit in RAM or else) or playing 3D games and whatnot. I thought moving to a 4200 RPM laptop hard drive was going to be bad, after my nice 7200 RPM IDE RAID. In truth, thanks to the Linux VM, I don't notice the difference after the first half hour of using the system. However, I did notice the big boost that came with moving from a PC100 memory system to a PC266, even just palying around with GUI wigets (resizing and whatnot).

Re:I always love...

[be-fan]

I always love morons who criticize things when they aren't part of their intended audience. Unless you're a gamer, you have no reason to be at those sites. If you are, those sites are invaluable. Quick, what's faster, the Radeon 8500 or the GeForce4 MX? I don't really care, my gaming is limited to some RPGs and the occasional CounterStrike match. However when I wanted to buy my brother a new graphics card, you bet he was happy that I did my research at those sites first. I used to frequent those sites a lot, back when I did a lot of 3D programming and gaming. I honestly needed the performance, and those sights provided a lot of good guidence, as well as useful ways to get cheap hardware to do cool things (overclocking Celeron 300A's and running them in SMP for example, or joining the bridges on Athlon XPs to get them running in SMP). As for the bit about advertisers, that's bull. The internet keeps these sites honest. A GeForce 4 TI 4600 really is a lot faster than a Radeon 8500. If a site says otherwise because of advertising, a second opinion (or third or fourth) is just a click away. In the future, it would be wise to provide specific proof before criticizing people of lacking journalistic integrity.

Re:But memory isn't the bottleneck anymore, is it?

[Jimmy_B]

Nowadays, you see all of these benchmarks on chips/chipsets/memory, and unless you're talking inSANE resolutions and color depths, AMD/Intel vs nVidia/ATI really doesn't matter much. It's just personal preference.

Resolutions and color depths have nothing to do with the chips/chipsets/memory; the component most affected by that is the video card. And if you think video cards are fast enough that choosing between nVidia and ATI is just personal preference, odds are you aren't doing anything which deserves more than an old 4-meg video card.

It was my understanding that the major bottleneck of any system is the DISK. So no matter how fast your ram is, if you still have to swap to the slow-ass disk, your system will be slow.

While starting up programs, yes, the disk is the bottleneck as files are loaded the first time. But for the tasks where speed *really* matters - compiling programs, long simulations, games - the speed of CPU and RAM are critical. (Disk can be made important if RAM is lacking in quantity, but with RAM prices as they are these days, that is inexcusable.)

politics

[GunFodder]

Via has not explicitly licensed the P4 bus. Via insists it has rights to the necessary patents through the purchase of Cyrix. If Intel officially approves this arrangement then they may lose some licensing sales in the future by setting a precedent.

The whole thing is kind of silly unless Intel is making money hand over foot in the chipset market. I wonder if their motivation to discourage 3rd party chipset development is to lock down control over various platform technologies? Sis currently makes P4 chipsets but they have a poor reputation for compatibility. Via has improved their rep by dominating the Athlon market. They might have the necessary market share to take the P4 platform in directions that Intel doesn't want to go.

Terrestrial cosmic ray intensities

[richard-parker]

Radiation(white noise) was always a problem with RAM, much more so at higher elevations(Colorado gets about 100x more ram errors than sealevel does, necessitating ECC ram)

Actually, the increased RAM failure rate due to the greater cosmic ray intensities at higher altitudes isn't as bad as you describe.

For example, the expected soft-fail rate of a computer memory system in Denver, Colorado is about 4 times greater than the rate expected at a city it sea level (such as New York City). Even in Leadville, Colorado (which is located at 10,151 feet) the expected failure rate is only about 13 times greater than in NYC. No location in Colorado even approaches 100x.

For more information, see the following paper:

J. F. Ziegler, "Terrestrial cosmic ray intensities", IBM Journal of Research and Development, Vol. 42, No. 1, 1998.

It can be found online here.