Dual Channel

[hurleyskate284]

I have a pretty noobish question but I have to know, so I figured, why not ask the experts here at the THGC. What is the benefit of Dual-Channel Memory? What makes it better (or worse) than normal Memory? Thank you in advance

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[blackphoenix77]

Dual channel memory gives you twice the bandwidth..like say normal PC3200 has 3.2Gb/s of bandwidth, well when you run in dual mode you will have 6.4Gb/s of bandwidth. But I still don't know if thats kind of like having 1024Mb of memory or what.

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[Crashman]

It's like having 1024MB of memory if you're using 2 512MB sticks! LOL

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[Coyote]

There's a big benefit for Intel chips, but for amd chips I keep hearing only about 5%, give or take (fron benchies peeps have run). So benefit depends greatly on cpu chip.

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[etp777]

Look out the window at the street. Most of us live on two lane streets. Imagine that there are no stop signs, but that all the cars are limited to the same speed. With only two lanes, not a lot of cars can get through. Imagine the street as being 4 lanes now. Cars are still limited to the same speed, but with twice as many lines, twice as many cars can pass through at a given tiem. This is a rough analogy to single channel over dual channel.

Now Nforce 2s don't use real dual channel, they use two seperate memory paths to sstagger memory timing(so chipset can access one while other is still waiting/responding to a request). P4s on the otehr hand are bandwidth hungryr, and can actually use it, so their dual channel is a real dual channel implementation(ie 7205/865/876 chipsets)

 

[krayzeemunkee]

Lemme get this straight...Dual channel is DDR2?? correct?

-Mac User-

 

[Coyote]

No, I think DDR2 is a new kind/version of ram (capable of higher FSB speeds). I'm not sure it's really out yet (unless in new vid cards).
EDIT: Yeah, its out.

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Win98SE<P ID="edit"><FONT SIZE=-1><EM>Edited by Coyote on 07/13/04 05:01 PM.</EM></FONT></P>

 

[hurleyskate284]

Another noob-ish Dual Channel question... I've been reading a lot of posts and everyone talks about how you install your RAM in what slots... I just installed mine to Slot 1 and 2 (Right next to each other)... Is that bad? Is there a certain way I'm supposed to install it to make it run more efficient? Maybe I'm just confused.

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[Cybercraig]

In a P4 board it is slot 1 and slot 3 or slot 2 and slot 4.
AMD can vary but 1 & 3 usually work for it too. Memory in slots 1 & 2 will give you single channel on a P4.


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[addiarmadar]

I am yet to notice a differnce between dual channel and single channel ram. On a good note with dual channel that they generally have better timmings.

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[hurleyskate284]

Yeah, I don't notice anything different about the Dual-Channel mode.

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[jammydodger]

AS Coyote said, with Athlon systems Dual channel mode will only give you a 5% increase (if that, I think its more like 3%). which is why you wont really notice the difference.

 

[hurleyskate284]

But I'm using Intel

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So.. Who's hungry?

 

[jammydodger]

oh, in that case you should notice a bit of a difference. What are your specs and what programs do you usually use?

 

[Guest]

System specs?
Depending on the Version of Your B4 the impact of dual channel can be less significant...
You can use Sisoft Sandra to check your memory bandwith. Run it in SC and after inDC youll see the difference.
Also you wont see the difference when browsing the Web, but if you do some memory intensive task you should be able to tell the difference!

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[Obtuse]

Here's the best explanation I've found. DDR400 RAM has an 8-byte bus. So... transferring 8 bytes at 400mhz = (8 X 400) = 3200 MB/S. On an AMD system, where the FSB is 400MHZ and 8 bytes, this means the processor and RAM have parity, as fast as the processor asks for information, the RAM supplies it. Now, we get into Intel procs, which run at an 800MHZ FSB. The Intel processor has an 8 byte bus width, so is requesting information at (8 X 800) = 6400 MB/S. So our same DDR400 can only satisfy half that requirement. What designers did then was basically make it so the motherboard could act like it had 2 seperate banks of RAM. So you run your 512 in dual channel. Now the processor sees these 2 seperate channels as one, big, fatty channel that is 16 bytes wide(kind of like using 2 water hoses to fill up a pool, the hoses actually put out the same amount of water, but to the pool, it's like one big hose). So now, our DDR RAM transfers data at (16 X 400) = 6400 MB/S, and once again has parity with the processor. This was also implemented in AMD (not the exact same way), but if you see above, it's not much better because the single-channel RAM could already supply data as fast as the AMD processor needed it.

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[hurleyskate284]

System specs:

Intel i865PE chipset, 2.4B Northwood, 512 Dual Channel Kingston DDR400 ValueRAM 2.5-2-2-7

If you need any other specs I'll tell you.

BTW, the RAM only runs at DDR266, since its synchronous with the CPU bus with the 133FSB. I overclocked to 138.7 FSB, so the RAM frequency is 173.4MHz.

<P ID="edit"><FONT SIZE=-1><EM>Edited by hurleyskate284 on 07/16/04 04:18 PM.</EM></FONT></P>

 

[jammydodger]

If you are running the RAM sycronously with the CPU the frequency should be exactly the same as the CPU i.e. 138Mhz (for your slightly overclocked system). Dual channel is probably more noticable on P4C CPU's which utilise 800Mhz (as opposed to 533Mhz) fsb's.

 

[dan6470]

I know that I have dual channel DDR in my system...but how do I know if its running in Dual Channel mode???

 

[hurleyskate284]

In the BIOs boot screen it will say "Dual Channel enabled" or, if you want to check easier, download CPUZ (Just do a google) and run it, and check the memory, it will tell you if you're running it in dual channel or single channel.

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So.. Who's hungry?

 

[dan6470]

ok...thanx alot

I dloaded cpu-z and it says in the "Channels #" box "dual" so I guess it is in dual channel mode...but in the "Performance Mode" box it says "disabled"...what does this mean?

 

[hurleyskate284]

Alright you have dual channel enabled. As to the Performance mode, I'm not totally sure. Mine says Enabled, it may be just with certain modules. I haven't messed with any settings, so I'm guessing it may just be with certain RAM.

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So.. Who's hungry?