Where do you see the benefits of Dual Channell DDR?

strokeside · Dec 11, 2002

From some of the reviews of Dual Channell DDR boards, there is only a small percentage performace gain (3% or less) when both channells are used as oppossed to one channell.

What is the exact area/circumstances where you would see a real benefit from dual channell DDR?
are there any?

I am mainly talking about using dual DDR with Athlon systems, as the Athlon is designed for using the bandwidth of a single channell DDR memory controller. I have not seen any reviews of dual DDR P4 boards, so I am aiming this at the Dual DDR Athlon boards.

Thanks.

the garynator · Dec 11, 2002

You would see the benifit of dual ddr when running a higher FSB. The reason you do not see much performance gain when running dual ddr on a regular athlon system is kind of like the reason that ddr400 did not offer a worth while performance gain. When the FSB is only running @ 266, in theory ddr266 would be enough to feed the fsb, but seeing that ddr266 doesnt always perform to its max is why the ddr333 gets so much better transfer speeds in a real system. When running a 333 or more fsb dual channel ddr will make a big difference with ddr266 versus single channel 266. This is becuase there is enough memory bandwidth to feed the fsb. hope this helps

Caffinehog · Dec 11, 2002

Seriously, with athlon, there is only one place that you will see major improvement: Integrated graphics.
Think about the old integrated graphics cards. They use memory bandwidth. With this setup, it could provide 3 times the memory bandwidth to the video card that pc2100 could.
In addition, the processor and video card will not always be competing for memory bandwidth.
Is it so much of a surprise then that nVidia developed this chipset?

PhobMX · Dec 11, 2002

Caffinehog said:
Seriously, with athlon, there is only one place that you will see major improvement: Integrated graphics.
Think about the old integrated graphics cards. They use memory bandwidth. With this setup, it could provide 3 times the memory bandwidth to the video card that pc2100 could.
In addition, the processor and video card will not always be competing for memory bandwidth.
Is it so much of a surprise then that nVidia developed this chipset?

hmm, never thinked about that. But bleh, integrated nforce2 video will never reach a radeon9700pro power no matter the oc..

Caffinehog · Dec 11, 2002

Quite true, Phob, but that kind of solution will be sufficient to play modern games. Maybe not at an awesome frame rate or resolution, but it will be a heck of a lot better than a cheap graphic card. And it will be cheaper than buying a board and a cheap graphics card.

snvpa · Dec 12, 2002

great point caffiene hog. I think that is the best reason for dual ddr. the other is to run pc 2700 at really aggresive timings at say 1/2 of the processor speed. therefore you could have the fsb for athalon at like 250 while the fsb for mem is like 125 and running at turbo timings. all the while the bandwidth of the mem is not wasted at all but used inb full by the processor. very effecient.

Anaxagoras1986 · Dec 12, 2002

Excellent point SNVPA, that sounds like an awesome idea. It would be awesome if they did that!

PhobMX · Dec 12, 2002

good idea indeed anaxagoras1986, also it might allow better cpu/mem ocs

Caffinehog · Dec 12, 2002

That idea is good, but it's not as good as it could be. Dual channel only performs about 5% better than single channel at the same speed. Sucks, don't it?

mateo · Dec 12, 2002

Caffinehog said:
That idea is good, but it's not as good as it could be. Dual channel only performs about 5% better than single channel at the same speed. Sucks, don't it?

5%??? Id like to see proof of that.

PC 800 RDRAM, in single channel, gives a theoretical max of 1.6 GB/s. This makes a theoretical dual channel bandwidth 3.2 GB/s, as seen in the 850x-860 chipsets. Sandra benches this at approximately 2.4-2.5 MB/s, which gives about a 50% or so increase over the theoretical single channel maximum.

Dual channel DDR, as benched in Granite Bay reviews, is slightly faster than RDRAM of the same speed. Considering the above figures, its certainly more than 5%. Also, while dual channel may not have as much bandwidth as some people expect, the low mem/high fsb divisor a good way to hit HIGH fsbs and/or utilize cheaper, slower, more common DDR.

Edited for clarity

RnPgrosz · Dec 12, 2002

Dual DDR really doesn't seem like a great reason to upgrade. I would be more interested in the Nforce 2 because of the potential of a higher FSB then a KT333 board could do. With the new BIOS from Epox people have been getting around 230 MHz FSB and higher. Although Dual DDR may not give such large gains it does seem like the memory bandwith is better then the Via chipsets even with a single stick.

Stumpjumper5200 · Dec 13, 2002

DualDDR doesn't make sense for an Athlon, they don't have the kind of bus bandwidth to handle the memory.

As for running the memory in dual channel, at a slow speed with really aggressive timings for "efficiency", try this: Corsair XMS. The PC3500 ram is rated up to DDR434 with CAS 2 and a 1T command rate. Timings may help get a little more out of ram in an Athlon system, where your severly limited for speed, but in an Intel system, forget the timings, just get the mhz as high as possible.

DualDDR is mostly an advance for Intel systems, and Athlons with integrated graphics. Finally, DDR memory with be able to fill up the P4's bandwidth, can't wait till I get a Granite Bay board.

Anaxagoras1986 · Dec 13, 2002

All NF2s have integrated GF4 MX440 right?

Caffinehog · Dec 13, 2002

Anaxagoras1986 said:
All NF2s have integrated GF4 MX440 right?

No. Make sure they have it if you are looking for this option.

Anaxagoras1986 · Dec 13, 2002

A7N8X?

PhobMX · Dec 13, 2002

Anaxagoras1986 said:
A7N8X?

nope

Caffinehog · Dec 13, 2002

Anaxagoras1986 said:
A7N8X?

No, the A7N8X does not have integrated video. In fact, the only board that has it so far that I know of is the 8RGA+, and I haven't seen that one on the market yet. I suspect you won't have to wait too long, though.

Just keep in mind that these boards have other features that are valuable. Several of them have lockable PCI busses, and all of them have lockable AGP busses. Also, many of these boards offer the widest range of Vcore and Vdimm options.
And there are reports of these boards running over 240FSB. In the last generation, anything over about 210 fsb was the holy grail of overclocking.

Dual DDR is only one feature to look at.

Anaxagoras1986 · Dec 13, 2002

Thanks for the info. I am pretty well informed about the feautures of it. I was just wondering if the A7N8X had it b/c I never saw them mentioning it on thier site. Who makes the 8RGA+? Epox?

Stumpjumper5200 · Dec 13, 2002

Sounds like an Epox name. As for the integrated graphics, it's a good idea for people that want to save money but not get shafted on performance. DEFINATELY need the DualDDR's bandwidth for that.

snvpa · Dec 15, 2002

yeah the 8rga+ is an epox board. you can see it on the epox website. its not oiut yet I'd suspect just after the 1st of the new year. I might actually buy that one as money has been tight lately and the integrated graphics would be alot better than my crappy ati rage 128/xpert 2000

Where do you see the benefits of Dual Channell DDR?

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