What the advantage of dual channel DDR when you don't have onboard video?

[propellerhead]

An excerpt from an Anandtech article:

Just like the original IGP, the nForce2 IGP supports a dual-channel DDR memory architecture that NVIDIA likes to call DualDDR (aka TwinBank). This 128-bit DDR memory bus gives the nForce2 the opportunity to exceed Intel?s 850E chipset in terms of raw memory bandwidth, but as we?ve seen before that only really matters when integrated graphics is enabled. With integrated graphics disabled, the second DDR channel is pretty much useless from a performance standpoint for the vast majority of scenarios.

This says if you are not using integrated graphics, the dual channel DDR doesn't really make a difference. Is this talking about motherboards with built-in video? If so, then why does the Biostar M7NCDP have dual channel DDR when it doesn't have built-in video?

What am I missing?

 

[Tom]

From the same article..

"The reason that adding more memory bandwidth doesn?t improve overall system performance is because the Athlon XP?s FSB is stuck at 133MHz offering up to 2.1GB/s of bandwidth "

Pentium 4s and newer Atrhlons run at faster than 133fsbs, therfore they can use the additional memory bandwidth that dual channel gives you to speed up virtually all processes. This is particularly true with the new Pentium 4 that uses 200fsb. (800fsb)

 

[jjyiz28]

http://www.gamepc.com/labs/view_content.asp?id=nf2so&page=1

read this. notice that dual channel 333 performs better than a single channel 333 for a 333 mhz athlon.
not only does dual channel double the bandwidth, which is more important for memory bandwidth hungry p4, but it also does interleaving. getting data from one memory channel while the other channel gets ready for transfer. results in better latency

edit: spelling

 

[propellerhead]

From the article jjyiz28 posted:

With two DDR-400 modules installed, nForce2 boards have the ability to utilize a whopping 6.4 GB/s of memory bandwidth. While even the newest Athlon XP processors don't come close to actually needing this much bandwidth in reality, it's nice to knows it's there down the road when faster Athlons may need it.

It appears I won't be seeing the advantage of Dual Channel DDR in my Athlon-based Biostar M7NCDP motherboard.

 

[pspada]

What I'm really wondering is what happens to duel (pun intended) channel when you put a 3rd DIMM in?

 

[jjyiz28]

Originally posted by: propellerhead
From the article jjyiz28 posted:

With two DDR-400 modules installed, nForce2 boards have the ability to utilize a whopping 6.4 GB/s of memory bandwidth. While even the newest Athlon XP processors don't come close to actually needing this much bandwidth in reality, it's nice to knows it's there down the road when faster Athlons may need it.

It appears I won't be seeing the advantage of Dual Channel DDR in my Athlon-based Biostar M7NCDP motherboard.

dual channel 400mhz does nothing for a 333mhz bus athlon, it even detriments it. did you read the whole article?? did you read the graphs on dual 333 having better performance in nearly all benchmarks than single 333 when onboard graphics arn't used?? did you read their explanations on this?? about interleaving, faster latency, etc...???

read this for comparison between dual 400, single 400, dual 333, single 333, using a athlon 333 bus cpu. dual 333 wins, then single 333, then dual out of sync, then single out of sync

http://www.gamepc.com/labs/view_content.asp?id=a7n8xd&page=1

 

[jjyiz28]

Originally posted by: pspada
What I'm really wondering is what happens to duel (pun intended) channel when you put a 3rd DIMM in?

i believe one channel is using one dimm slot, while the other channel uses 2 dimm slots as strange as that may seem. if you fill up all three slots, you are still in dual channel.