Dual Channel Memory help...

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jackal858@sw.rr

I am building a new system in about a month. I am not a hardware wizz, and have a question dealing with RAM selection. I have been told that Dual Channel memory is the way to go, offering more speed than normal RAM.

My real question is, what is the difference between a pair of 2 x 512 Dual Channel memory sticks, and a pair of 2 x 512 "normal" memory sticks? And do you think it is worth the extra (about) $60 for the Dual Channel over the non Dual Channel?
 
Any 2 sticks of memory (or 3 sticks depending on the Mobo) can be run in Dual Channel Mode, providing they are the same capacity (or same capacity per bank on some mobos e.g. 2x256 and 1x512), the same speed (e.g. DDR400 PC3200).

All a "Dual Channel Memory Kit" is, is 2 sticks of matching RAM, that has been guaranteed to run in a dual channel configuration. This is a ploy by the manufacturers to try and cut down on the amount of technical support they have to provide, because Joe User already has some memory, and hears about Dual Channel offering a performance boost, goes out and buys more memory (slightly different speed or latencies) and his machine does not work stably with it.

Therefore, buying a dual channel memory kit is probably not worth the extra cash to most experienced users, as aslong as you buy 2 sticks of branded memory (e.g. Crucial, OCZ, Kingston, Corsair, Geil etc.) at the same time from the same supplier, they are likely to be identical and work fine, and you will have saved yourself around $60.
 
Thanks a lot. Will save me about $60 off this new build then, which is nice. That is kind of the idea I had gotten from other people also, and didn't understand why this specific memory kit cost more. I was afraid it was a ploy, and am glad I asked.

This is the config I am looking at, any suggestions are welcome:
ASUS P4P800 SE I865PE motherboard
Intel P4 3.2 gighz
2 x 512 Corsair PC3200 Dual Channel (or maybe not since post)
BFG 6800GT OC 256mb
Samsung 120gb 7200RPM HD
Creative Sound Blaster Audigy2 ZS
 
thanks...

Hey all...

I just wanted to say thanks for the info...as this is exactly the question I had as well..

peace..
 
I have a ASUS P4P800-E Deluxe motherboard. It says it takes Dual-Channel DDR400 Memory but can i only buy one stick of memory or do i have to buy two?
 
I don't think you must have two, but of course you lose the benefits of having two.
i am new to this building your own lark, and last year I built a machine with an Asus A7N8X deluxe mobo and put in a matched pair of Adata 256 DDRs. Later, thinking that more is better, I added another Adata 256. Does that mean I have lost the benefit of the Dual Channel by having three in?
 
If you only use one memory module, the motherboard will switch back to Single channel mode & you will lose quite some performance. It will still work though so if you have no other choice, you can always use one module & get a second one when you have the chance to do so.
 
What was forgotton to say is your motherboard has to be able to support dual ram for it to work.. Sure you can only run one stick right now then add a stick later but check your manual for dual channel to be active..Example I have a Asus A7N8X-E DELUXE for dual to work has to be in dimm a1 and dimmb1 or dimma2 and dimmb1 or to have dual with all three they all have populated with the same size sticks as in other dimms all this is in you manual with proper configs.
 
Dual Channel memory helps

Read thru the discussion board, I am still not convince mysefl that 2 identical single memory sticks will work for dual channel. The dual channel memory usually has double sides chipset where as the regular has only one side of chipset. Anyone in here have tried to put 2 identical single side memory stick in the motherboard. Does it work? I doubt it.

dtp2005
 
dtp2005 said:
The dual channel memory usually has double sides chipset where as the regular has only one side of chipset.
Click to expand...
That has nothing to do with it. The only thing really running in a Dual-Channel manner is the memory controller which is either on the CPU (Athlon64-939/Opteron) or on the chipset (nForce2, i865/i875/i915/i925, etc.).

The amount of memory chips on the module does not indicate if it will work in a DualChannel system or not. & BTW the only difference between normal memory modules & "DualChannel" memory modules is an extra validation process for the latter. when they are being sold with the label "DualChannel", it just means that they (Corsair, Crucial, Kingston, etc.) have tested them in a such a configuration & that they are guaranteed to work in such a configuration. There's no physical difference between the two.
 
I'm about to get an ASUS "A7V880" VIA KT880 MoBoard with 4 DIMM slots..

I am only going to get two sticks of 256 right now to work in DUAL Channel, but if I get two more sticks down the road, will it still work as DUAL Channel with all 4 DIMM slots filled ?
((assuming they are matching pairs, but maybe one pair of 256, and another pair of 512, or does that matter ?))

thanks, peace.. :suspiciou
 
They all have to be the same in each dimm slot to work .. Example they all have to be either 256,or 512 for the dual channel to work..

ausu great boards I highly suggest them.
 
pizzada said:
I'm about to get an ASUS "A7V880" VIA KT880 MoBoard with 4 DIMM slots..

I am only going to get two sticks of 256 right now to work in DUAL Channel, but if I get two more sticks down the road, will it still work as DUAL Channel with all 4 DIMM slots filled ?
((assuming they are matching pairs, but maybe one pair of 256, and another pair of 512, or does that matter ?))

thanks, peace.. :suspiciou
Click to expand...
That depends on mobo makers on how they brought the physical addressing traces out, it is always best to get 2 identical single-sided memory sticks if you do want dual channels...

The dual-sided memory sticks have greater fan-out loading than single-sided memory sticks and tended to fail as the clock speed goes up, or multiple dual-sided memory sticks being used simultaneously which doubling and quadrupling the fan-out loading - way way too much input capacitive loading for faster clock speed performance.

When your mobo used buffered memory sticks instead of typical unbuffered then it's a different story.
 
What about the CAS latency of the memory and the clock? If they are the same brand and size but different CAS latency, Do they work as dual channel as well? Also, what about the FSB of the motherboard, suppose if you use 4 banks of memories each memory is 400Mhz the total is 1600Mhz, if the motherboard has FSB only 800Mhz, Is that possible the motherboard will slow down the memory speed to 200Mhz to get full bandwidth, or the motherboard must do something to keep up those memory?
 
dtp2005 said:
What about the CAS latency of the memory and the clock? If they are the same brand and size but different CAS latency, Do they work as dual channel as well?
Click to expand...
In that case, you have to force manual mode for the lowest common denominator CAS settings from the worst latency memory device, the memory controllers typically are fixed, they don't switch base access parameters per device during operation.

Typically, the mobos which allowed 2 seperate dual-channels memory sets also allowed "different CAS per controller" but not "different CAS per memory device".

Some mobos simply will become disable, no dual-channels mode and no other selective choices.
dtp2005 said:
Also, what about the FSB of the motherboard, suppose if you use 4 banks of memories each memory is 400Mhz the total is 1600Mhz, if the motherboard has FSB only 800Mhz, Is that possible the motherboard will slow down the memory speed to 200Mhz to get full bandwidth, or the motherboard must do something to keep up those memory?
Click to expand...
AMD64 series had no external FSB. Intel's version and older Nvidia's NFORCE series used stored and forward techniques, the FSB remained identical... dual-channels or not dual-channels.
 
Not many motherboard out there that has a function in the bios to allow you to set the CAS manually. Do you know any good P4 motherboard that allows you manually set the CAS? The best P4 motherboard that I have ever seen is GA-8KNXP Ultra 64, this board is rock, it has everything you need.
 
dtp2005 said:
Not many motherboard out there that has a function in the bios to allow you to set the CAS manually. Do you know any good P4 motherboard that allows you manually set the CAS? The best P4 motherboard that I have ever seen is GA-8KNXP Ultra 64, this board is rock, it has everything you need.
Click to expand...
Can't help you there, I no longer used Intel hardware but just a hobby from in-born curiosity now and then. I no longer have sufficient exposure to a larger database of Intel experience.
 
Well, how about this...

What is likely to be quicker...2 256 sticks running in DUAL channel.....OR 4 256 sticks running regular ?

And would either one be better or worse for the system overall, as in wear n tear ?
 
Well depends one the bandwith will be faster in dual channel but your comparing 1 gig to 512 run some badwith test with dual than run same test with 1 gig the test you will run is memory read memory write hope this makes sense to you.. The bandwith will be higher in dual than in single mode..
 
How about the scenario, 4 sticks of 256MB each 200Mhz so total is 800Mhz and 2 sticks of 512 400Mhz, which one will run faster? My understanding the dual channel optimized for double bandwidth compare with the single channel. Single channel share the same pipeline for read and write data where as the dual is read and write data access different pipeline.
 
Hi

I have a similar issue. Had a 512 Mb DDR400 dual-sided DIMM, and later purchased stock 512 Mb DDR400 (which turned out to be single sided).

Intel 915 chipset recognised the dual channel memory configuration of the 2 sets, but reports a clock speed of 333Mhz, rather than 400Mhz.

Checking each memory stick individually, they both CAN run individually at 400Mhz - has anyone else experienced this?

_____
 
SAPStar said:
Hi

I have a similar issue. Had a 512 Mb DDR400 dual-sided DIMM, and later purchased stock 512 Mb DDR400 (which turned out to be single sided).

Intel 915 chipset recognised the dual channel memory configuration of the 2 sets, but reports a clock speed of 333Mhz, rather than 400Mhz.

Checking each memory stick individually, they both CAN run individually at 400Mhz - has anyone else experienced this?

_____
Click to expand...
Didn't you read what I had written above about fan-out and clock speeds? You're one of those with newer mobos which actually down clock as REQUIRED and NEEDED automatically.

Your mobo can't drive 4 sticks at 400, but do just fine at 333. Most mobos can't, some Nvidia's will do 400 if they're all single-sided sticks.

4 single-sided sticks have the equivalent fan-out loading as 2 double-sided sticks.
 
Thanks for your assistance. I'm new to this, so appreciate your help.

For my clarification, if my 2nd DIMM was DS rather than SS, would the clock speed have remained as 400Mhz? (Likewise, if I changed for 2 xSS)? The intel documentation on their support site for dual channel makes a big play around not mixing SD and SS, but as above it can work.

Also for memory transfer rate, how would 1x512Mb @ 400MHz (Single Channel) compare to 2x512Mb @ 333MHz (Dual channel)?

There is a lot of confusion over numerous internet forums regarding this, so any help gratefully received.
 
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