Hi,

I'm having trouble getting two 512mb memory sticks to work properly in dual channel mode on my computer. My system specs are as follows:

Gigabyte GA-K8NF-9 (Latest bios drivers - F7)
nForce4 4x
AMD Athlon64 3500+ S939 2.2GHz
2x DDR 333mhz CL2.5 memory sticks (1 is branded RAmos, the other has no brand name)
ATI Radeon X800XL 256MB PCI-E

The problem I'm having is to do with getting dual channel mode to recognise 1GB of memory on my system, because at the moment it is only recognising 512MB of memory. My system only reads both memory sticks when they are working in single channel mode. I took the memory sticks to my computer parts supplier, he tested both sticks on his computer and had no problems. I'm not sure if he was running the memory in single or dual channel mode though. I've read the manual for my motherboard, I've read through different forums (including this one), and I've read the article explaining dual channel memory at this website: (www.hardwaresecrets.com/article/133/1). None of these helped with my problem. There is an interesting part in the article though, that discusses how instead of the chipset controlling dual channel mode, Athlon64 S939 cpus handle dual channel memory via an embbeded Dual Channel memory controller (Page 6).

Does anyone here have a solution to my problem?

I understand that to run in dual channel, both sticks of RAM need to be identical, from the same manufacturer and with the same number of chips.

Good Luck
Smitty

You could be right. I might need to check that with my supplier.

I just checked the specifications for each of my memory sticks using cpu-z. I found out that both sticks are different, not only in brand, but also in specs. The RAmos is a 512mb PC2700 166mhz. The other memory stick, which is made by AM1 I think, is a 512mb PC3200 166mhz. That's probably why dual channel mode isn't working. I'm going back to test out some other memory at my supplier's store tomorrow. If none of the memory there works, I'll probably order in a new RAmos memory stick, since my RAmos memory stick (I found out a few days ago was bad RAM) is still under warranty.

Definitely get your warranty's worth, but may I suggest to go with the former rather then the latter. That is, the higher the bandwidth (pc3200) the better. Two pc3200's in dual config will yield a theoretical transfer rate of 6400mb/s. Combine that with your already fast intergrated FSB of 2.2ghz, and you'll have a winner.

I do know (being an intel guy, next rig will be AMD) that this config benefits A p4 more, cause it creates equilibrium, A 800mhz FSB = 6400mb/s, thus DDR ram at 200mhz = 400Mhz, then add another stike in dual channel you will get double, or 800mhz that is equal to the chipset's FSB.

People demand freedom of speech as a compensation for the freedom of thought which they seldom use.
--Kierkegaard--

* "stike" is spelled "stick"... gotta love the edit button

People demand freedom of speech as a compensation for the freedom of thought which they seldom use.
--Kierkegaard--

Yeah, I got told to do that on another forum (http://forums.techguy.org:80/t404417.html). Thanks for the information. I'll definitely go for another AM1 512MB PC3200 400Mhz, that way I'll get the most I can out of my CPU :).

I just realised. What about CAS latency? If I buy two PC3200s, I'll have to run my memory at CL3, instead of using two PC2700s at CL2.5. I've read that there is a considerable difference in performance between the two latencies. Is it worth sacrificing latency for bandwidth?

ahhh yes...

CAS latency, refers to clock cycles, how long data needs to wait before receiving or transmitting a charge (process of sending and reciveing). So a CL of 3 means a packet of data will be sent or retrieved every three clock cycles. The mainstream standard is 2.5, while the hardcore enthusiast will settle for no less then a CL2 which (to my knowledge) is the lowest they go.

"Is it worth sacrificing latency for bandwidth?"

I believe you mean to ask, is higher mhz better then tight latancy? This is the current case of DRR2 right now, DRR2's native frequency is 533mhz, but its downfall is that it takes forever to access data, becuase of its 4,4,4,11 timings ( first number always being the CL). Tests have shown DDR2 is at par with standard (pc3200)DDR running with lower timings. Its a work in progress though, and DDr2 is improving considerably.

People demand freedom of speech as a compensation for the freedom of thought which they seldom use.
--Kierkegaard--

Oh ok, so would it be better to buy two 512mb DDR PC3200 400Mhz CL3 memory sticks, or 2 512mb DDR PC2700 333MHz CL2.5 memory sticks? In other words, which configuration would be a better choice for a relatively equal balance between performance and stability in dual channel mode?

better buy 2 512 PC3200 PC3200
you can downclock them to PC 2700 and get the same latency(2.5)

Athlon 64 2800+ @ 2.63 Ghz Stock Cooling
Timings:2-3-2-5
V-Gen 512MB pc3200
DFI Lanparty UT NF3
Abit R9550 VGuru XTurbo
525Mhz/300Mhz

"I understand that to run in dual channel, both sticks of RAM need to be identical, from the same manufacturer and with the same number of chips".

I have said this way too many times, you DO NOT need to have 100% identical memory sticks to run in dual channel mode, that is a feature of the board and not the sticks. While it may be the ideal to do that, it is not a fundamental criteria, the sticks do not even have to be of the same size or manufacturer,but you definitely want sticks of the same speed.

BTW Fel,

A64 2800+ @ 2.63 w/ stock cooling, how'd ya pull that 800MHz OC off, don't tell it's the DFI. With a 9X multiplier, are you telling me you're clocked at 292Mhz ?

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Hi Fel and Sabretooth,

Fel - If I was to downclock them to PC2700, would that decrease the mhz. Would it then become 333mhz? If so, I might as well just buy a PC2700 memory stick. Oh, I'm also interested in how you oc'd your cpu that high as well.

Sabretooth - I thought that was the case with memory sticks. But like you say, they need to be the same speed. Although... my PC3200 is able to run at 166mhz. Could I downclock the PC3200 memory stick in my computer to 166mhz, and run both memory sticks in dual channel mode? If so, how could I go about doing this?

skulleh & sabertooth -
actually,
it is 7.5 * 350 MHZ (HTT speed)
while memory/HTT speed = 1/2
so memory = 175Mhz @ 2-3-2-5
running at... PC 2800?
i can pull it off to 2.7Ghz, but it runs unstable.

when i oc my CPU, it runs at 51-54C underload. 56C at max load.
pretty hot.
but at underload on default clock, my cpu runs at 49C, so not a major difference.
maybe it is bios problem, because my friend's A64 3200+(default, newcastle) runs at 42C on MSI.

skulleh -
just prepare for future use, so when you upgrade, you won't have to buy new memory stick. but do what your heart feels, if you feel like to buy PC2700 then buy it.

i never run my memory on 1:1 configuration, because A64 runs best with tight timings. so i run it at 1:2, that means my memory = 100Mhz@cl2-2-2-5, while cpu runs at default speed (1800Mhz).

oh yeah and sorry, because your name was isaac, and i thought skulleh is someone else using P4 system, so i recommend on buying PC3200.
but still, i prefer to buy PC 3200, you can oc higher.

Athlon 64 2800+ @ 2.63 Ghz Stock Cooling
Timings:2-3-2-5
V-Gen 512MB pc3200
DFI Lanparty UT NF3
Abit R9550 VGuru XTurbo
525Mhz/300Mhz

Why not just get 2 x 512MB PC3200 CAS 2.5 RAM to begin with? Even if your PC2700 is 2.5...if you got another stick to match, you'd sacrificing 33MHz bus speed, which in dual channel mode equates to a loss in bandwidth of approx 1067MB/s (5333MB/s vs 6400MB/s)

ASUS A7N8X-X
Athlon XP 1800+
8.5 x 200MHz
1024MB PC3200 2.5-3-3-7
Asus A9550GE/TD 128MB
WinME/WinXP Pro SP2

Fel - Thanks for the advice. I bought an extra 512mb PC3200 memory stick. The 2 sticks run fine in dual channel mode, so I'm happy about that. I'll probably leave them running at 400Mhz CL3, because I don't know much about overclocking, although I'm interested in it. If I wanted to overclock my PC3200 from CL3 to CL2.5, would that be an easy process that wouldn't stress my memory too much? If it is easy and won't cause crashes and BSODs on my computer, I might try it out.

jam - I couldn't find any PC3200 memory sticks with a CL less than 3. My computer parts supplier said they didn't have any. Anyway, I might end up overclocking my two PC3200 memory sticks to CL2.5.

CL2.5 or CL3, you realise you are talking nanoseconds performance gaps here. I do not recommend sacrificing stability for that type of performance disparity.

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Ok, so it's probably not worth it, but I'm still going to read up and learn about memory overclocking for furture reference.

I take it you don't buy memory online?? Newegg has plenty of PC3200 CL 2.5 RAM. Here's just one example:

http://www.newegg.com/Product/Product.asp?Item=N82E16820220057

Changing the memory timing is as simple as going into the BIOS & changing a few settings. If the system becomes unstable, just change it back. My RAM is also Kingston PC3200 CL 3.0, but I changed the timings from 3-4-4-8 to 2.5-3-3-7 quite some time ago & I've had no problems whatsoever.

Have a look at these articles:

http://www6.tomshardware.com/motherboard/20040119/index.html

http://www.devhardware.com/c/a/Memory/Memory-Bandwidth-And-Timings/

ASUS A7N8X-X
Athlon XP 1800+
8.5 x 200MHz
1024MB PC3200 2.5-3-3-7
Asus A9550GE/TD 128MB
WinME/WinXP Pro SP2