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Single Channel Dual Channel.. What the hell???

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April 22, 2006 6:20:06 AM

Ok i got 2 sticks of PQI 1gb DDR Dual channel memory..
and one stick OCZ 512mb singl channel memory

when i have the 2 pqi i get dual channel at 200mhz ~ 2gb ram
when i have a pqi and a ocz i get single channel and 400 mhz ~1.5gb ram
and if i flip flop the pqi i get single channel at 200mhz ~ 1.5gb ram

WHAT THE HELL IS GOING ON HERE??

the rig:
ECS K8T890-A (<~~ yeah i know but it came in a combo kit..)
AMD 64 X2 3800+
Memory: well you know that already
PCI-E EVGA 6600GT

so what is the deal??
is it better to have 1.5gb @ 400mhz in single channel?
or is it better to have 2gb @ 200mhz in dual channel??

why is it 200 mhz in dual channel??

this lame ass dual channel crap is really starting to confuse me..

any help please!!?? Thanks..
April 23, 2006 10:45:47 PM

Dual channel is supposed to out perform single channel so use the two PQI sticks.

Are the PQI PC2100?



Please note I know nothing about dual channel or single channel. Take a nap and get at it after your bloodsugar and caffiene level is normal.
April 24, 2006 3:05:51 AM

...said this once in another thread....will say it again here, repeat after me...

There is no such thing as dual channel memory. It is the chipset/mobo that supports dual channel - any memory that fits into that chipset/mobo, will run in dual channel if you put the 2 sticks into the proper slots.
Related resources
April 24, 2006 3:08:27 AM

as for what is going on, it is likely going with teh initial slot to determine which memory setting to go with......so when you flip them y ou get different answers.

Dump the 512 stick and go with the matching sticks, making sure you put them into the proper slots.


(for me it is slot 1 and 3 that are the first dual channel combo, and 2/4 is the 2nd...that I have empty).

As soon as you put in a 3rd, you will not be running dual channel, because the 4th is empty.......so dump the 512 and you will be better off.


[edit: I over simplified this and skipped details, but that in effect is the deal]
April 24, 2006 3:39:36 PM

Quote:
Dual channel is supposed to out perform single channel so use the two PQI sticks.

Are the PQI PC2100?


No it is PC3200..
April 24, 2006 3:44:48 PM

Quote:
as for what is going on, it is likely going with teh initial slot to determine which memory setting to go with......so when you flip them y ou get different answers.

Dump the 512 stick and go with the matching sticks, making sure you put them into the proper slots.


(for me it is slot 1 and 3 that are the first dual channel combo, and 2/4 is the 2nd...that I have empty).

As soon as you put in a 3rd, you will not be running dual channel, because the 4th is empty.......so dump the 512 and you will be better off

[edit: I over simplified this and skipped details, but that in effect is the deal]


Actually the mobo only has 2 memory slots.. so im kinda limited in that.. and im not sure if i explained it correctly but i getting thoes results using two...

im still confused because if i use the 2x1gb then i get only 200mhz.. but i get 400mhz when i use the 1x512 and 1x1gb...

i think im just going to live with 1.5gb and the 400mhz bus.. i get 10 more FPS in the doom3 test this way.. i dont know why...
April 24, 2006 4:57:33 PM

Quote:
Ok i got 2 sticks of PQI 1gb DDR Dual channel memory..
and one stick OCZ 512mb singl channel memory

when i have the 2 pqi i get dual channel at 200mhz ~ 2gb ram
when i have a pqi and a ocz i get single channel and 400 mhz ~1.5gb ram
and if i flip flop the pqi i get single channel at 200mhz ~ 1.5gb ram

WHAT THE HELL IS GOING ON HERE??

the rig:
ECS K8T890-A (<~~ yeah i know but it came in a combo kit..)
AMD 64 X2 3800+
Memory: well you know that already
PCI-E EVGA 6600GT

so what is the deal??
is it better to have 1.5gb @ 400mhz in single channel?
or is it better to have 2gb @ 200mhz in dual channel??

why is it 200 mhz in dual channel??

this lame ass dual channel crap is really starting to confuse me..

any help please!!?? Thanks..





For best results you need a matched pair of memory sticks ( identical ).

Like this:

http://www.newegg.com/Product/Product.asp?Item=N82E1682...

2x184pin DDR400 PC3200 SDRAM


If your memory sticks are not identical then the motherboard will have to slow down to the speed of the slowest memory module.
April 24, 2006 5:14:14 PM

dual channel has to be in pairs. Can't run 3 sticks of memory in dual channel.
April 24, 2006 5:23:02 PM

i really hate it when people dont read...

I shall reiterate..
this board DOES NOT HAVE 3 RAM SLOTS.. it only has two.. i can only use 2 sticks of ram.. not 3.. only 2... thank you...
April 24, 2006 5:37:37 PM

Use the 2 same-size sticks!

That 400mhz you are seeing is a bad bios report. That is NOT correct.

There is no way in hell it is running at that.

The 2 matched sticks in dual channel will be far faster than the 1.5...
April 24, 2006 5:54:38 PM

Do you have the Ram timings of the 2 identical Ram modules? Sometimes the eager or just plain lazy bios updaters don't update the RAM dection timings properly therefore causing the motherboard to miss read your ram timings. Try to manually input the RAS/CAS timings to make sure the memory is represented properly. Just to be sure :) 

Hope this helped!
April 24, 2006 6:08:18 PM

Quote:
are you sure that mobo has dual channel capabilty? put both 1GB sticks in and go into your bios and see what it says their?


why does a motherboard without dual channel capability say "dual channel" at post? it has to have that capability.. right?
April 24, 2006 6:16:00 PM

Quote:
are you sure that mobo has dual channel capabilty? put both 1GB sticks in and go into your bios and see what it says their?


why does a motherboard without dual channel capability say "dual channel" at post? it has to have that capability.. right?


Yes it IS a dual channel board.

For best results you need 2 IDENTICAL memory sticks.

You can combine different sticks but you cannot expect it to work correctly.

Your memory sticks are also different sizes that configuration is unsupported.
April 24, 2006 6:20:26 PM

Quote:
are you sure that mobo has dual channel capabilty? put both 1GB sticks in and go into your bios and see what it says their?


why does a motherboard without dual channel capability say "dual channel" at post? it has to have that capability.. right?


Yes it IS a dual channel board.

For best results you need 2 IDENTICAL memory sticks.

You can combine different sticks but you cannot expect it to work correctly.

Your memory sticks are also different sizes that configuration is unsupported.



Quote:

Dual-channel architecture DDR SDRAM describes a motherboard technology that effectively doubles data throughput in the frontside bus from RAM to the memory controller. Dual Channel-enabled memory controllers utilize two 64-bit data channels, resulting in a total bandwidth of 128 bits, to move data from RAM to the CPU.

In order to achieve this, the DDR SDRAM memory modules must be installed into matching memory slots, which are usually color coded on the motherboard. Each memory module in each slot should be identical to the one in its matching slot. It's also possible to use similar memory sticks from different manufacturers or different production series as long they are of the same size, specification, the same number of memory chips and internal organization.
April 24, 2006 6:29:38 PM

Quote:
are you sure that mobo has dual channel capabilty? put both 1GB sticks in and go into your bios and see what it says their?


why does a motherboard without dual channel capability say "dual channel" at post? it has to have that capability.. right?


Yes it IS a dual channel board.

For best results you need 2 IDENTICAL memory sticks.

You can combine different sticks but you cannot expect it to work correctly.

Your memory sticks are also different sizes that configuration is unsupported.



Quote:

Dual-channel architecture DDR SDRAM describes a motherboard technology that effectively doubles data throughput in the frontside bus from RAM to the memory controller. Dual Channel-enabled memory controllers utilize two 64-bit data channels, resulting in a total bandwidth of 128 bits, to move data from RAM to the CPU.

In order to achieve this, the DDR SDRAM memory modules must be installed into matching memory slots, which are usually color coded on the motherboard. Each memory module in each slot should be identical to the one in its matching slot. It's also possible to use similar memory sticks from different manufacturers or different production series as long they are of the same size, specification, the same number of memory chips and internal organization.



perfect.. now i have a better understanding of dual channel.. although my origional question was not answered.. im just going to leave it at a crappy motherboard.. ECS was never any good to me anyways..

thanks everyone...
April 24, 2006 6:35:32 PM

Quote:
Dump the 512 stick and go with the matching sticks, making sure you put them into the proper slots.

(for me it is slot 1 and 3 that are the first dual channel combo, and 2/4 is the 2nd...that I have empty).

As soon as you put in a 3rd, you will not be running dual channel, because the 4th is empty.......so dump the 512 and you will be better off.


Your thinking of a Socket A board, in which case you'd be correct, however the OP is using a socket 939 board.

Quote:
That 400mhz you are seeing is a bad bios report. That is NOT correct.

There is no way in hell it is running at that.

The 2 matched sticks in dual channel will be far faster than the 1.5...


Again, we are dealing with S939, so 400MHZ is possible. However you're correct in that the OP should stay with the 2 matched sticks.

To the OP. Download the manual. Pages 14-17 should help clear up the confusion. Especially pages 16-17.
a b } Memory
April 24, 2006 6:40:22 PM

I didn't see anyone mention this, but isn't a 200mhz fsb/htt DDR400, thus the double data rate? My bios reads as 200mhz, but at post it shows dual channel DDR400 128 bit. When I oc to 220mhz 1:1 I get DDR440.
April 24, 2006 7:09:01 PM

That's what I meant by 400MHZ is possible.

BTW, 400MHZ is also possible with Socket A. I know because that's what my Athlon XP-M 2600's memory is running at. Also the last XP Barton's released supported 400 FSBs.

bombasschicken, don't be ashamed by your 7600GS. From what I hear it's a solid card for the money.
April 24, 2006 7:31:43 PM

Let's make some clearness :-)

200MHz reported by BIOS settings is correct, beacuse it's the real SDRAM clock frequency and isn't related with the HTT speed at all (remember that HTT on AMD is not like FSB on Intel!).

DDR400 is the Double Data Rate speed: the memory exchanges data at 400MHZ because it uses both edges of the 200MHz clock, but all the commands are synchronized with and sent at 200MHz clock speed.

Related to the dual channel stuff, the previous posts are correct: you must have 2 modules of the same size, speed and timings in order to use dual channel capability.
Dual channel is not a capability of the RAMs itselves, it is a capability of the RAM controller: in practice the two slots are configured in parallel, doubling the thoretical maximum bandwidth, but obviously the two DIMMs have to be identical in size and speed to do so.
April 24, 2006 8:06:37 PM

dual channel out performs single channel by doubling the memory bandwidth by the chipset.now on most older dual channel boards you can run two sticks of similar ram in the apropriate slots and you get dual channel.however,todays boards (like my evga) are more finicky and require identical ram or it will only read as single channel.as for putting a third stick in,make sure it is the same make and size and speed as others.else you will get the problems you are having now.hope i have helped.

evga nf4 sli mainboard
athlon 3500+(soon to have a 4400+dual core)
7800gt
2x1gig samsung ddr400(dual channel)
wd 300 gig hd.
ace 520watt ps
April 24, 2006 8:08:01 PM

Quote:
Dump the 512 stick and go with the matching sticks, making sure you put them into the proper slots.

(for me it is slot 1 and 3 that are the first dual channel combo, and 2/4 is the 2nd...that I have empty).

As soon as you put in a 3rd, you will not be running dual channel, because the 4th is empty.......so dump the 512 and you will be better off.


Your thinking of a Socket A board, in which case you'd be correct, however the OP is using a socket 939 board.

Quote:
That 400mhz you are seeing is a bad bios report. That is NOT correct.

There is no way in hell it is running at that.

The 2 matched sticks in dual channel will be far faster than the 1.5...


Again, we are dealing with S939, so 400MHZ is possible. However you're correct in that the OP should stay with the 2 matched sticks.

To the OP. Download the manual. Pages 14-17 should help clear up the confusion. Especially pages 16-17.

First, my board is a s939 board and if I don't use 1 & 3 for my sticks, it does not report it as dual chanel. If I use 1 & 2 for example it goes single channel.

Second, I'm well aware that 400 is possible, not with what he put in it! He stuck it in rebooted and it reported it one way, all he did was flpy the 2 different size sticks around and tried again and it mis-reported it. So based on what he did, it is impossible for it to be running at that.
April 24, 2006 9:04:35 PM

Ooops, my bad. I misread your initial post. Didn't see the 2/4 part.
April 24, 2006 9:30:52 PM

perhaps this is a little OT at this point, but yes you can. maybe a 939 won't allow it, but I have 3 sticks in dual channel on a socket A that are quite happy. channel A -- two 256MB OCZ & channel B -- one 512MB GeiL, dual channel 400MHz 2.5-3-3-6-1T. ok, i'll grant you it was a pain to get it working, but they work. some combinations wouldn't POST, some would give errors, but there was a way to do it.
April 24, 2006 10:30:07 PM

joex444 is right: in theory it doesn't matter the size of each module, what counts is the total amount of RAM installed in each channel.
I have 2x512MB modules in channel 0 and 1GB module in channel 1 in an A8N and it worked great since the first boot.

However It doesn't works on all mobos because of bugs or limitation in BIOS FW, but the RAM controller itself doesn't matter for the single module size: the two channel configurations are totally independent (except for frequency and timings that *MUST* match) if it doesn't work it's a FW related problem.

At work we design system boards for very high speed realtime image processing and we tested theese strange configurations with Intel, AMD and Freescale, and always worked fine with well written FW.
April 24, 2006 10:30:31 PM

Yes, I'd be interested in seeing some CPUZ screenshots of that.
April 24, 2006 11:02:54 PM

You can't run a 256 and a 512 in dual channel, it doesn't work at all!

If you ipotetically could do a thing like this, passing the 512MB barrier (2x256) would lead to errors, because the RAM controller can't switch the bus width on the fly: it runs always at 64 bit or always at 128, it can't do a thing like you wrote, it is a non-sense.

I spoke of a setup of 2x512 + 1x1GB or 2x256 + 1x512: as I said the total memory amount of the two channels *MUST* match.
April 25, 2006 11:27:25 AM

There is no proof to provide, we do not use silly tools like CPUZ or similar, we write out own FW and also design our own boards for our purposes, so we verify the RAM controller operation with logic analyzers because BIOS and software reports are often erratic with strange configurations.

However speaking of standard commercial mobos We tested the Asus A8N and the MSI K8N with standard BIOS FW and they work with theese two configurations:

2x256MB CH0 + 1x512MB CH1
2x512MB CH0 + 1x1GB CH1

Strangely they don't work if you exchange the two channels, putting the odd modules in CH0.
I don't know if other mobos work like theese, you must try, but the 3 modules must have the same speed and timings capability.

If I understood well your first post you have a 2 slots only mobo, so it is much better for you to use the 2 identical modules and go dual channel: no mobo at all can work with 512MB on CH0 and 1GB in CH1, this is impossibile, even changing the BIOS.
April 25, 2006 12:20:55 PM

If the POST tells you that the memory runs in dual channel it is right, I never seen errors in this. The errors usually regards frequency and timings, but dual/single channel mode was always reported correctly by POST in all the mobos I've seen.

If you are still in doubt you can use a benchmark program (the good old memtest86 is perfect in this!): doing a RAM bench you can tell if you are running in dual channel by the bandwidth reported.
April 25, 2006 12:45:29 PM

Sorry, but you are wrong in a thing: it's a non-sense to say that "the third stick is a normal sitck", all the sticks are normal!
As I said the sticks are all identical, they do not know what dual channel is, it is the RAM controller that address them in dual or single channel mode: we have designed and tested a system board for Texas 6600DSP with a Quad Channel DDR2 controller using standard Kingstom 1GB modules.
It's a controller issue only the capability to drive the modules in dual channel or not.

The AMD integrated controller is able to run 3 modules in dual channel, you can read this in the official AMD Datasheet (you can found the document on the AMD website). All that matters to the controller is the total RAM amount of the two channels that must be identical, as in the 2 example configurations I mentioned.

But the BIOS also must support theese strange config, because it is BIOS responsibility to read and process the modules SPD and program the AMD RAM controller accordingly.

So it depends on two factors: RAM controller (the AMD one can do that) and the BIOS, and this is a mobo related factor.
April 25, 2006 2:07:43 PM

I repeat this works on A8N (normal, SLI not tested) and K8N: double or single sided doesn't matter for a well written BIOS FW it is only a PCB related and chip availability thing to use single or double sided modules.

My modules are double sided and work, but as I said it depends on mobo FW: as an example it works for me on the A8N, but doesn't work on the A8V.
April 25, 2006 3:16:49 PM

I think you made a wrong assumption: the 2 512MB modules have to be mounted on the same channel, making a total of 1GB on one channel, equals to the single 1GB module mounted on the other channel.

Let you have a 4 slot mobo: 0 & 1 on CH0, 2 & 3 on CH1.
If you put two 512MB modules on slots 0 & 1 they'll use the 64bit bus of CH0 and will be addressed in sequence (there are dedicated address decoders on RAM controllers that do this): they will be concatenated in a unique contigous array of 1GB.
This is how *ANY* memory bus works, not only the PC ones.

The two channels are 64 bit each, no matters how many modules you put in the slots. Obviously the BIOS FW must be able to program the address decoders in the right way in order to access the modules in the correct way: the majority of them (like Via) will disable dual channel operation if they found different number of modules per channel, regardless of their size.

And there is an explanation for this: the very first DDR mobos only had 3 slots, because of problems in PCB traces and bus drivers that did not garantee signals integrity with 4 slots. With theese mobos you could only use 2 modules in dual channel or 3 in single channel, because of trace delays problems.
Many BIOSes are still inherited from this old stuff, thus not allowing the 3 modules configuration.

As I said many times, it is only related to the BIOS FW ability to correctly recognize the RAM configuration and properly program the RAM controller and this is not an easy issue: SPD data aren't standard at all and many SPD chips contain wrong parameters (as reported in many articles by TomsHardware itself!) and this is why, in our image processing system boards, we often reprogram the SPD chip with new correct values.
April 25, 2006 5:17:24 PM

I will soon have access to an Abit KN8 SLI, 2x512MB DDR PC3200 and 2X1GB DDR PC3200.

I will test the idea and run the 2 512s in CH0 and 1 of the 1 GB in CH1 to see if it works in dual channel and report back on the matter.

Forgive us yanks, but what's a lorry?
April 25, 2006 5:37:00 PM

Ohh, thanks. I figured that's what you were talking about, but wanted to be sure.

We have several terms. Semis ( :oops:  ), tractor trailers, diesels, big rigs.....

When I used to work for NCR, some of our ATMs came out of Dundee. We had a few design problems and some of your Dundee boys had to come out and give us a hand. I quickly learned the terms torch, spanner....

However, if it wasn't for the young guy that came with them, I would never have known what the older guys were saying. Apparently it was english, but...damn. Hah, I'm sure they probably said the same thing. The younger guy was more in tune with American culture and had to act as a translator.
April 25, 2006 6:44:15 PM

NO....I really thought he wanted a blowtorch!!

I remember the first time one of the older dudes spoke to me.

Quote:
Ughh klook bok duuk thouhg!

My eyes glazed over with that deer in the headlights look. Then it dawned on me...the man was a Klingon.

Actually, he just wanted to know where the restroom was.
April 25, 2006 7:14:30 PM

Bog may have been somewhere in that phrase. It was back in 2000, so it's hard for me to remember. Hell, I remember when I didn't know what the "head" was when someone referred to it instead of the restroom (that was back in ole 95).

As I noted before, I will be getting my hands on some new (well new to me) equipment and should have something up and running for testing by this weekend. I'll post my results if I have time to get to it.
April 25, 2006 7:53:28 PM

Quote:
back on subject i still want to see proof of this tri-channel memory solution this guys is going on about. its the only term i can come up with to explain how three sticks can work in dual channel mode. i have never heard of this. the scary thing is he might be telling the truth and everyone on these boards have benn telling lies all this time 8O


i kinda understand the concept of dual channel now.. so it makes sense for 2 sticks only.. however why would they intentioally make a dual channel board with only 3 slots? unless its possible to have the tri-channel thingy... although i could be wrong...
April 26, 2006 12:46:13 AM

Quote:
...said this once in another thread....will say it again here, repeat after me...

There is no such thing as dual channel memory. It is the chipset/mobo that supports dual channel - any memory that fits into that chipset/mobo, will run in dual channel if you put the 2 sticks into the proper slots.


As long as you fit similar memory into the right slots, it will work?

Say I get another Kingston ValueRAM 512MB stick of RAM, same one I got in now, If I put it in the other slot for dual channel then it will work properly?
April 26, 2006 2:00:45 AM

ok.. so help me figure this one out...

i decided to test the two better configs.. the 2gigs and the 1.5 @ (what the bios says) 400mhz

my real world test, being that i am mostly using this machine for gaming, is a FPS test in doom3.. the "timedemo demo1 usecache" thingy.. so i ran the test in both situations..

ok now everyone says use the matching pair of 2 gigs.. however...

when i use the 2gigs i get 58.9FPS
when i use the 1.5gb i get 62.8FPS

I ran this test 3 times on each config, defraged, and a restart between..

yes i know this is not real benchmarking but this is how i like to figure the best configs...

and i know its only 4FPS but its still better for some reason..

so what do you guys think?
!