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Confused. What makes DDR ram duel channel?

Last response: in Memory
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March 15, 2007 2:10:47 PM

I understand the motherboard has to support it, but what about the ram. Is so called duel channel ram made different than single channel ram or just packaged that way by being tested together? Or is it all about the controller on the motherboard.
I have an ASUS A8N5X motherboard that supports duel channel. I have 2x 512 samsung and 2x 512 patriot ram. Should I be able to run either two or all four of these in duel channel? Both sticks of each are the same.
March 15, 2007 2:16:51 PM

Theoretically it'll work. The best way to find out is try it. Is it all rated for the same speed/timings?
March 15, 2007 2:51:58 PM

All 4 sticks are not exactly the same. I think the samsung is rated at 3-4-4-8 and the patriot at 2.5-3-3-6.
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March 15, 2007 2:55:09 PM

When I only had two x512 sticks the bios did not recognize it as duel channel. And even with all 4 x512 it doesnt either. I shouldnt have to make it recognize the ram as duel channel should I? That should be automatically. CPU-Z also show it as single channel.
March 15, 2007 3:39:17 PM

It's really all up to the motherboard and how finicky it's going to be with dual channel.

Many of the older boards will only work in dual channel with matching sticks of ram. The newer boards have become a liitle more flexible and you can often mix brands/speeds/timings. Your mobo manual should give you an idea what to expect, but it's always worth trying.

Incidentally if your board allows it, and you mix sticks of different speeds or timings they will all run at the settings of the slowest stick.
March 15, 2007 6:46:47 PM

[quote="openchut82"... Is so called duel channel ram ... just packaged that way by being tested together?[/quote]
Yes, exactly.

As for your problems getting dual ("duels" were outlawed hundreds of years ago) channel mode to work, try it first with just 2 exactly identical DIMM placed in the correct sockets according to your MB manual (should either be in the 1st and 2nd sockets, or 1st and 3rd sockets). If that doesn't work, try it the other way (manuals are often wrong).
March 15, 2007 7:16:29 PM

Quote:
I understand the motherboard has to support it, but what about the ram. Is so called duel channel ram made different than single channel ram or just packaged that way by being tested together? Or is it all about the controller on the motherboard.
I have an ASUS A8N5X motherboard that supports duel channel. I have 2x 512 samsung and 2x 512 patriot ram. Should I be able to run either two or all four of these in duel channel? Both sticks of each are the same.


Here's what I found:

Dual-channel architecture DDR/DDR2 SDRAM describes a motherboard technology that effectively doubles data throughput from RAM to the memory controller. Dual channel-enabled memory controllers utilize two 64-bit data channels, resulting in a total bandwidth of 128-bits, to move data from RAM to the CPU.

In order to achieve this, the DDR/DDR2 SDRAM memory modules must be installed into matching banks, which are usually color coded on the motherboard. It is not required that identical modules are used, but it is often recommended. One module of 512MB RAM could be installed in bank one and a 1GB module could be installed in bank two. Modules rated at different speeds can be run in dual channel, although the motherboard will then run all memory modules at the speed of the slowest module. Some motherboards however have compatibility issues with certain brands or models of modules when attempting to use them in dual channel mode. For this reason it is generally advised to use identical pairs of memory modules and most memory manufacturers now sell "kits" of matched pair DIMMs. Several motherboard manufacturers only support configurations where a "matched pair" of modules are used. Dual-channel architecture is a technology embraced by motherboard manufactures and does not apply to memory modules. In other words, any matched pair of memory modules may support single and dual-channel operation, provided your motherboard supports this architecture.



-http://en.wikipedia.org/wiki/Dual-channel_memory
March 16, 2007 12:52:39 AM

Unfortunately, that wikipedia entry illustrates wikipedia's all-too-frequent characteristic of not quite getting it right. For example, in the first paragraph, the data is moved from the RAM to the memory controller, not the CPU. The nature of the memory-controller/CPU connection is usually different than that of the memory-controller/RAM connection.
In the second paragraph, "One module of 512MB RAM could be installed in bank one and a 1GB module could be installed in bank two." is true, but at least some (and perhaps all) of that memory won't be running in dual channel mode.
March 16, 2007 10:43:30 AM

Aye, unfortunately I just posted it for a quick answer.

I've always been told "dual channel" memory is more of a marketing scheme as the motherboard as to support dual channel.
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