What is and How to do a duel channel ddr thingy?

[LoopyJuice]

There isn't really a HUGE performance increase in using dual channel, just another gimmik, i've got a couple of stick of 256mb Corwsair XMS3500 in dual channel here on the tightest timings possible with processor at stock (old locked xp1800 palimino core which won't go past 143FSB ) still a nice thing to have...

[Donny John]

Are we better off running at tighter timings, or is actual memory speed more important?

so, would 2 6 3 3 @200mhz be better than 2.5 8 4 4 @210mhz?

Or is there an optimal compromise that can be achieved?

[Agent]

Originally posted by LoopyJuice
There isn't really a HUGE performance increase in using dual channel, just another gimmik, i've got a couple of stick of 256mb Corwsair XMS3500 in dual channel here on the tightest timings possible with processor at stock (old locked xp1800 palimino core which won't go past 143FSB ) still a nice thing to have...

Yup, the gain from Dual DDR is not huge, a few 100mb/sec at best, but any performace gain is welcome in my books, no matter how its done !

Originally posted by Donny John
Are we better off running at tighter timings, or is actual memory speed more important?

so, would 2 6 3 3 @200mhz be better than 2.5 8 4 4 @210mhz?

Or is there an optimal compromise that can be achieved?

Check my reply in Zaks thread
Basicly there is not much between them. in my experience i have had better results from relaxing the timings a little and going for the higher FSB, but it is best to benchmark both and see which one yields the best results for you

[steve threlfall]

The three slots found on the nf7 are arranged as follows:

Slot one (often labelled as slot 3) makes up bank one

Slots two and three (ofetn labelled as slots two and one) make up bank two.

Bank two should be physically apart from bank one. For dual channel to work both banks must have the same amount of memory inserted.

Get the ram that in my sig from komplett cheap and ace

[Agent]

Originally posted by steve threlfall
The three slots found on the nf7 are arranged as follows:

Slot one (often labelled as slot 3) makes up bank one

Slots two and three (ofetn labelled as slots two and one) make up bank two.

Bank two should be physically apart from bank one. For dual channel to work both banks must have the same amount of memory inserted.

Get the ram that in my sig from komplett cheap and ace

Sorry mate, but each DIMM slot is acctually 2 banks. I dont know where you have got the idea that slots 2 and 3 are a bank in their own right, its not. Banks 2 + 3 are acctually 4 Banks if you add them together. Which makes a totaly of 6 Banks on the NF7

Secondly you dont need the same amount of memory installed in each slot for Dual DDR to work.

Too many people think Dual DDR is RAID for memory, its not.

[Trickle]

Originally posted by Agent
RAM does not need to be the same size for Dual DDR to work.

I think I'm going to need evidence for this one Agent. I'll bow and scrape and apologise to you later if I'm wrong.

/em heading for a fall here

[Agent]

Originally posted by Trickle
I think I'm going to need evidence for this one Agent. I'll bow and scrape and apologise to you later if I'm wrong.

/em heading for a fall here

Well think of it like this. There are 2 memory controlers on the NF2. While one deals with 2 sticks (slots 1 and 2, Banks 1->4) and the other deals with just the one stick (Banks 5+6). They opperate totaly independent of each other, they only come into contact inside the northbridge. Latency is lowered this way, and because they have no relation to each other, sizes of RAM cant effect each other.

The "memory must be the same size" myth came about when the NF2 chipset was still under beta stages and hardwares sites assumed things, and started them as facts. So many people read this and didnt think twice of it, afterall its not as if it couldnt be true, it sounds perfectly feasable.
To prove this to you i even have to reflash my BIOS to the latest version. Can you agree with me that there is no way to get 768MB of RAM in a system without using 2 sticks of different memory sizes ?. 512Mb+512MB = 1024MB, 256MB+256MB = 512MB, so the only way to get 768MB would be to have a 512MB stick and a 256MB stick, correct ?
Right, thats what ive got in my system, 1 stick of 512 and a stick of 256.
here is your evidence then . Sorry about the pic quality, but im sure you know how hard it is to get a good picture of a monitor. Ive turned the flash off for one, and left it on for the other

Now bow down and take it like a man like Zak did

Tell me if ive missed anything !

[steve threlfall]

Sorry for the confusion agent. By banks i meant the groups of slots where the memory is inserted eg the two slots together and the slot on its own (physically apart). Hope this cleras thing up

[Agent]

You were still wrong on the memory front

Basicly for Dual DDR, just start at DIMM 3 and work towards DIMM 1, then you'll be using Dual DDR , simple

[Trickle]

I'll have to take your word for it agent until I get round to installing something that can open .rars later.

However, I say it stands to reason that if the 2nd memory controler is accessing only 256Meg then its not going to be operating in Dual mode quite to the extent of 512/512.

So to say that you get dual DDR /w 256+512 isnt entirely accurate either as 2/3 of your mem is stuck on 1 controler? I had assumed the rar was a sandra bench jpeg, but at 1.7meg what is it? You say its a pic of the monitor? Is this a bios screen shot?

[Zak33]

Originally posted by Agent
you just get 2 sticks of RAM and put them in slots 2 and 3 for it to activate
It'll use 2 memory controlers as opposed to one

Now I use Slot 1 and 3 cos thats what shows up as Dual Ram in BIOS for me

[Agent]

Trickle - rar is basicly the new windows zip format.
Gimmie 2 mins and ill upload it again in zip

[Agent]

Originally posted by Trickle
I'll have to take your word for it agent until I get round to installing something that can open .rars later.

However, I say it stands to reason that if the 2nd memory controler is accessing only 256Meg then its not going to be operating in Dual mode quite to the extent of 512/512.

So to say that you get dual DDR /w 256+512 isnt entirely accurate either as 2/3 of your mem is stuck on 1 controler? I had assumed the rar was a sandra bench jpeg, but at 1.7meg what is it? You say its a pic of the monitor? Is this a bios screen shot?

Why do you think that the second one is only accessing 256meg ? - if that was the case, you would only see 512 of the RAM in POST, and as it doesnt and shows all ram, whats taking charge of the other 256mb then ?. Its going to be the same as 512/512 as the memory controlers dont talk to each other - all the work is done at the northbridge. Before Dual DDR, one memory contoler would do all the work for DIMMS 1,2 &3. Now DIMM's 1 & 2 are run by one controler, and slot 3 is run by another controler. So instead of the controler controling 3 slots, its only doing 2 (slots 1 + 2), with a dedicated one to slot 3. You should beable to put any RAM size in, and aslong as the 2nd memory controler is being used, then its using Dual DDR. It leads to less overhead for the controlers and less latancy for the second controler doesnt have to wait around for the first to do its stuff on slot 3.
Thats all Dual DDR is - spreading the load across 2 controlers. Its nothing fancy like RAID.

Ive uploaded again here

[Trickle]

Thanks for the zip file. I've used rars in the past - abandonware and roms have a habit of coming in that format (which is annoying).

> Now DIMM's 1 & 2 are run by one controler, and slot 3 is run by another controler.

With 512/512 the memory controllers would be at 50%/50% of total memory. With 512/256 you are at 66/33%.

Therefore the benefit of being Dual DDR is only going to come into play ⅔ as much on the 2nd system. So the Dual ddrness™ of system 2 isnt going to be working as hard as it is on system 1. A bios screenshot doesnt distinguish between the difference.

Now, whether the Nvidia drivers are designed to make sure the 2nd 256meg of the big 512 stick gets filled up last is another matter. So far I'm only speculating. I'ed like to see some Sandra benches - not that I'ed trust Sandra to test all 756meg of mem in all scenarios, but I'll trust their programmers to know more than me guessing here

[Agent]

Originally posted by Trickle
Thanks for the zip file. I've used rars in the past - abandonware and roms have a habit of coming in that format (which is annoying).

> Now DIMM's 1 & 2 are run by one controler, and slot 3 is run by another controler.

With 512/512 the memory controllers would be at 50%/50% of total memory. With 512/256 you are at 66/33%.

Therefore the benefit of being Dual DDR is only going to come into play ⅔ as much on the 2nd system. So the Dual ddrness™ of system 2 isnt going to be working as hard as it is on system 1. A bios screenshot doesnt distinguish between the difference.

Now, whether the Nvidia drivers are designed to make sure the 2nd 256meg of the big 512 stick gets filled up last is another matter. So far I'm only speculating. I'd like to see some Sandra benches - not that I'ed trust Sandra to test all 756meg of mem in all scenarios, but I'll trust their programmers to know more than me guessing here

Why would it be at 50%/50% ?. Its got two memory controllers, so surely it would be 100%/100% as each one is controlling a DIMM of RAM ? (now i dont know for certain, but as controller 1 has DIMMS 1&2 and Controller 2 has DIMMS 3&4, wouldnt it make sence that if only one stick of RAM was used in each of the controllers it would get 100% of its resources as its got no other sticks to deal with ?)
Now you've raised a good point here. Say i had a system with 512 in DIMM 1, 256 in DIMM 2 and 256 in DIMM 3 would this be 50%/50% | 100% or 66%/33% | 100% ? or something totally different ?, i really would like to know if more percentage of power is given to the sticks with more memory, or if its a time based system meaning they all get the same.
Interestingly Gigabyte are the only mobo making that uses the Nforce 2 and has 4 DIMM slots. I'm going to download the manual and see what it says about it.
Even with us not being sure on the %ages that each RAM module gets in terms of resources, can you agree on me now that Dual DDR (even though we don't know how much yet !) does work with 2 different sizes and will have some benefit ?

[steve threlfall]

Originally posted by Agent
You were still wrong on the memory front

Basicly for Dual DDR, just start at DIMM 3 and work towards DIMM 1, then you'll be using Dual DDR , simple

Thats what i did with mine but for some reason i couldnt seem to make an sense writing it here

cheers matey