Okay I keep hearing that running my ddr400mhz ram in dual channel mode is useless because my A7N8XE-Deluxe FSB is only 400mhz.While I understand the reason,WTF would they advertise the board as being dual channel DDR, 400Mhz FSB, and DDR 400 if it really doesn't matter because you won't get any performance boost running in dual channel? Now if I had a P4 800mhz FSB running paired sticks of DDR400mhz i would get a boost. If this is some sort of creepy ass marketing ploy for the uneducated then I am a little dissapointed in ASUS. Or it could be that I'm a complete tard and am totally wrong.

There is some debate about the merits of dual channel ram with AMD processors. Theoritically what you say is correct. The issue may be that memory isn't always used to process data when charged. Sometimes the memory is purged by processor instructions. To go into this any further is beyond my understanding. Suffice to say this. When AMD dual channel MBs first arrived on the scene there were many tests run. Some tests showed no increase in total system speed and some showed a 5% increase. I personally think that in reality the MB costs me no more to buy so why not go for it. What I won't do is buy matched ram for the board if it costs more than 2 individual sticks. I am running dual ram now at 333 with kingston value ram that wasn't matched. Bought the ram on sale with rebates. If the dual channel hadn't worked, I would have simply moved one stick and not worried about it. I bought the board because of the other features. I am using onboard sound, NIC, USB. The MB cost $61 us. Many OCers may get more benifit from the extra bandwidth. Besides, eventually AMD will move to higher FSB and the The field testing will make that a smoother transition. If you paid extra buck for matched ram don't dispare, at least it should OC better.

There really is no such thing as dual-channel memory. There are two sticks of memory that have tested together in a dual-channel motherboard to make sure there are no timing problems. The pairs are sold together with total size given. For example, Corsair's TWINX memory kits consist of a pair of DDR RAM that have been tested as a pair in an Asus A7N8X dual channel motherboard.

Dual-channel motherboards have two memory controllers while others have only one. In 2002 only the ASUS A7N8X was dual-channel for the AMD CPUs. VIA has added the dual-channel KT880 for AMD CPUs. Intel joined in and added a number of chipsets for the P4 and Xeon that are also dual-channel. An example is the Intel 875P chipset.

Benchmarks have shown about a 5% increase in speed for dual-channel operation. Real world apps will probably show less. So you see even if is mostly a marketing ploy it must be working since even Intel has joined in.

What do you mean, "Intel joined in"? Intel started the whole thing!

To understand dual channel DDR & it's "usefulness", you have to understand bandwidth. I don't wanna get into another long explanation about this, but bandwidth is determined by FSB. If you take the FSB & multiply times 8, you'll get the bandwidth in mb/sec. At 400FSB, the bandwidth is 3200mb/sec. Hmmm, doesn't that number look familiar? What's the bandwidth (or throughput) or PC3200 RAM...3200mb/sec! They match perfectly! Very interesting...

Now put the PC3200 in dual channel mode on a board running at 400FSB...the FSB bandwidth is still 3200mb/sec, but the RAM throughput is now 6400mb/sec (3200 x 2). They don't match, therefore the RAM is "bottlenecked" by the FSB

Now let's put the PC3200 in dual channel mode on a board running at 800FSB...the FSB bandwidth is now 6400mb/sec, & the RAM throughput is 6400mb/sec (3200 x 2). They match perfectly again!

What's the moral of the story? AMD/AtlonXP/400FSB = bad...Intel/P4/800FSB = good! LOL!

Here's an interesting read about dual channel performance:

http://www.sudhian.com/showdocs.cfm?aid=480&pid=1769

egkenny. I think you totslly missed the point i was trying to make. I know that there's no such thing as dual channel ram. What I was trying to say is that if your FSB is 400 MHZ and your ram was 400mhz what's the point of having a dual channel configuration on an AMD board that only supports 400mhz fsb? Now of course intel would jump on it since their bus speeds go in excess of 800mhz and the boards can support the increased transfer rate of dual channel DDR.

Amen brother Jam! Now if someone could please tell me WTF!!! an AMD board that has 400mhz FSB is even doing with dual channel?

ganubis understands the concept

;)

Hey ganubis, if you check the link I posted, I think it pretty much answers your question...here's a clip:

"It’s a high-tech version of the Emperor’s New Clothes, a game of one-upmanship where neither side is willing to admit how far from reality the game has gotten. Why did Intel focus on memory bandwidth? Because it was a big number they could tout. Why did AMD focus on dual-channel configurations? Because Intel had dual-channel configurations. And everyone (even the people for whom it couldn’t possibly matter) bought into it, because we learned somewhere along the way that two is better than one."

I don't really think that AMD is completly responsible. The nForce2 chipset and then Via's entry into the market are what folks are buying. AMD more or less got out of the chipset business awile back. As far as my spin on the usefulness of dual controllers is concerned, read my post above. I might add that in the future AMD will no doubt move to higher FSB and dual controllers will become more relevant. Right now there is no harm if you don't spend extra cash on matched memory.

Dual channel is "theoretically" useful on the P4 system running the higher FSB of 533 or 800. It's also useful on the Athlon64 system. However, the chances of running a program that require this much bandwidth are highly unlikely.

On systems running at 400FSB or less, dual channel's not necessary & there's little or nothing to be gained by it. But I agree there's no harm in running it.

I've read, in this post, mention of the Asus A7N8X motherboard... which is what i have. What is racking my head is the whole "400MHZ FSB" thing. I believe that i have a 400MHZ AthlonXP 3000+ CPU (WCPUID shows "AMD Athlon[tm]XP 3000+" on the name string field). When i boot up & enter the BIOS, the maximum CPU setting i can have is 200Mhz. Is this because my CPU FSB is actually running @ 200MHZ?

Similary, when i run WCPUID, it says the system clock is around 200Mhz, but the system bus is at 400MHZ. With a default multiplier of 10.5, it has to be a 400Mhz FSB Athlon XP 3000+, right?

For the Ram side of things, i have 2, 512 PC3200 sticks... put in slots 1 & 3. When having the memory settings set to "Auto" the resulting speed when i'm booting up is 200 MHz, in dual channel mode. Is this right, or should it be saying 400MHz?

At the end of the day, if the net gain is only 0-7%, then i really don't care. i just thought i'd ask.

amd at the supposed 400Mhz is "dual pumped" meaning its actualy frequence is 200Mhz it accessess memory twice in the clock cycle. Intel is "Quad Pumped" its core fsb frequency is only 200Mhz but it accesses the memory 4 times in a cycle. thats y maybe the mother board is recognizing only 200Mhz when u think its supposed to show higher. Because dats the True Frequency of the bus. The chipset architecture is the difference in the "quad or dual pumped" thing. its a scam technically speaking cuz they aint running at that frequency!
does this help?

One fact the most people are missing here in the single vs.dual channel debate is that the CPU is not the only thing using memory bandwidth. You have AGP, Network DMA, hardisk DMA, PCI devices DMA, and Audio DMA all trying to get access at that memory bus along with that CPU. I would like to see the *net* effect or system wide impact of having that dual channel memory controller in the AMD boards vs. the Single channel. Personally, I have the A7N8X-X, which is single channel cause the price point was right when I bought it, but I think for the power user/gamer, that dual channel may actually provide some performance gain that isnt realized in the CPU benchmarks.