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GunshyGabe
06-19-05, 01:27 AM
I have 3 dimm slots on my asus a7n8x deluxe 2.0. Dims 2 and 3 have 512 each for 1gig of xmsC2 memory for my system in dual channel. I want to add more memory like a 1gig or 512 stick on my 1st and final open dimm, but I don't want to lose dual channel. Can this be done without me losing dual channel, by having my 3 dimm slots populated? Thanks!

jAkUp
06-19-05, 01:40 AM
I am pretty sure you will lose dual channel once you put the 3rd stick in.

Pandora's Box
06-19-05, 02:22 AM
I am pretty sure you will lose dual channel once you put the 3rd stick in.


nope you wont loose dual channel. i have 2 sticks of 512MB in slots 2 and 3, and 1 more 512MB in slot 1. still have dual channel.

gram_vaz
06-19-05, 02:49 AM
yup, though with the third stick it's just partial dual channel.

not like dual channel makes much difference anyway.

rewt
06-19-05, 05:49 AM
Gabe asked me this very question. Since I didn't really know the answer (and I wanted to know myself) I directed him here. Thanks for the help guys :)

P.S. - gram_vaz I believe dual channel does help in some situations. Such as when the CPU is so fast the RAM cannot always keep up. The second channel provides a pathway for more data thus preventing a waste of CPU clock cycles.

jolle
06-19-05, 06:22 AM
CH2 is shared on Slot 2&3 I think..
Optimally you want equal amounts of RAM in each channel, so you can have for ex 1x512mb in CH1 and 2x256 in CH2, or 1x1gb + 2x512Mb.

If the amounts are uneven, its supposedly only running partial Dual Channel..
According to the info at NforcersHQ forum about DC, if you put in 3x512, only 2 of them will be in Dual Channel, while the third is left in Single since it has no "mate" to be "raided" with.. so to speak..
Swap one of the 512mb against a 1Gb and then you should get full DC.

Dazz
06-19-05, 06:40 AM
Yeah DUal channel will work with the nForce2 even with three slots, Dual channel may add 1~2% to system peformance. Not much really. With my MSI board i had 256MB 128MB and 512MB in the same board and got dual channel.

jolle
06-19-05, 08:18 AM
The main thing with DC on Nforce2 is lowering latancy I think.. since the AthlonXP FSB cant take more bandwidth (I think).
But it runs the modules in interleave (sortof like RAID) which lowers the access time since it accesses CH1, then CH2, then CH1, pretty much cutting the latancy in half..

So the benefit would be dependant on how Latancy dependant the benchmark is, games are traditionally Latancy "hungry", since its often alot of small chunks of data accessed more or less randomly... where Bandwidth is good for large predictable streams or chunks..

GunshyGabe
06-19-05, 09:57 AM
So it looks like from what I currently have. Which is a 512mb stick in dimm 2 and a 512mb stick in dimm 3 for a total of 1 gig system memory. My best option would be to put a 1gig stick in dimm slot 1 for optimal performance with my setup and to still have dual channel. Thats sounds good to me. I'll be ordering my 1 gig Corsair now that I know all this. Thanks guys for all your help and the education on dual channel. I really appreciate it.

gram_vaz
06-19-05, 11:54 AM
^ but the 2x512mb in slots 1 & 2 and the 1gig stick in slot 3. that way you'll have 1gig in channel one and one gig in channel two.

ricercar
06-19-05, 02:49 PM
Dual channel requires the same capacity in both channels. If you have 512M+512M in one channel, you need 1G in the second channel, not one 512M.

I've configured a dozen nForce2 boards with 256+256/512. As long as the RAMs were all rated the same speed, there was never a problem getting it recognized as dual channel, even mixing Corsair, Mushkin and Crucial.

Pandora's Box
06-19-05, 07:15 PM
Dual channel requires the same capacity in both channels. If you have 512M+512M in one channel, you need 1G in the second channel, not one 512M.

I've configured a dozen nForce2 boards with 256+256/512. As long as the RAMs were all rated the same speed, there was never a problem getting it recognized as dual channel, even mixing Corsair, Mushkin and Crucial.


well considering im running 2x512 in one channel and 1x512 in another and dual channel is working absolutely fine your statement is wrong.

Dazz
06-19-05, 07:44 PM
Dual channel requires the same capacity in both channels. If you have 512M+512M in one channel, you need 1G in the second channel, not one 512M.

I've configured a dozen nForce2 boards with 256+256/512. As long as the RAMs were all rated the same speed, there was never a problem getting it recognized as dual channel, even mixing Corsair, Mushkin and Crucial.
Worked pefectly fine for me with 128MB + 256MB Crucial PC2100 and 512MB TwinMOS PC2700. Came up as dual channel.

ricercar
06-19-05, 08:45 PM
That's fascinating. Goes against everything I learned working at NVIDIA on the nForce2 memory controllers. Well, I've been wrong before and I'll be wrong again. Best of luck to you.

The Roman rule: "The one who says it cannot be done should never interrupt the one who is doing it."

Have you actually determined that you have better memory bandwidth, or are you simply trusting a BIOS POST screen notification? A BIOS POST message isn't infallable.

jAkUp
06-19-05, 09:08 PM
Worked pefectly fine for me with 128MB + 256MB Crucial PC2100 and 512MB TwinMOS PC2700. Came up as dual channel.

WTF??! How could that be possible? For dual channel the memory HAS TO be the same. Same with RAID'ing hard drives, same with running SLI. It all works the same when it comes to computers. Not to mention, your PC2700 was probably running at 2100.

gram_vaz
06-19-05, 11:11 PM
yes, an uneven pair will work in two channels though it's only partial dual channel. like me and ricercar have said both channels have to be even. from what i remember dual channel works in 128bit. an uneven capacity of mb in the two channels will only have the third stick run in partial dual channel(96bit).

Kojiro
06-20-05, 02:29 AM
Direct Memory Access is reason why Dual channel is good for Nforce 4.

Try running Doom 3 with Aperture set to 256MB. the dual channel helps from the card to system memory.

As well as DMA channels on hard drives and CD-RWs/DVD-RW drives will have less imact on system performance.

Having dual channel reduces system to memory traffic. CPU will have much more chances to have the full 2.7 GBps memory bandwith it's FSB allows.