Who needs dual-channel DDR anyway

Well I'm pretty sure you can't run 3 DIMMs in dual-channel mode.
I think if you check closely you will see that you can run 3 DIMMs, but only at PC2700 speed.
Does your rig run 400MHz(DDR) FSB?
If so, you must pick the 2 DIMMS that most closely match (CPU-Z can be useful for doing that) and run 1024MB at full speed.
If you desire more memory at high speed and in dual-channel, you must run 2 x 1024MB DIMMs.
Trust me it's not worth it, trading stability for an extra 512MB ;^(
If your rig is not rock-solid, it takes all the relaxed joy out of doing ANYTHING with it...
Regards

 

cheers, you're probably right about the speed thing, but its still unstable even with only 2 dimms in, it doesn't matter which dimm is in which slot,its always unstable with more than 1 dimm in, but fine with any 1 dimm in any slot. I've gone back to 512 for now, but I've got some work coming up that requires a lot of firepower and i need to get this sorted, but i can't understand whats goin on.

oh yeah, 400mhz fsb and ati 9800aiw 128.

 

I just spoke to tech support at crucial, and apparently the problem is the A7N8X-E with barton 3200cpu becomes unstable in DDR400 mode...
Has anyone else heard of this, or any solutions?
They reckon I can run in dual channel mode at 333mhz or single-channel at 400mhz.(by using slots A2 & A1)
So I'm running 2x512 in single channel at 400mhz mode at the mo.
I use the computer for graphic not gaming so I reckon this is the best compromise.

 

Tell them agent-k said they are talking out of their arse.

what a load of old cobblers, thats just a cop out.

 

Good advice to check flash BIOS often (maybe weekly :^)
Many others like you, as this is popular 'mainstream' mobo.
Actually I have heard of this - my own rig runs in this fashion:
333 Dual (PC2700 speed) OK.
400 Single (PC3200) OK.
400 Dual (PC3200) NFG - not stable!
Having to choose between 333 Dual and 400 Single, and having some overheating problems, I have set my CPU back to stock XP2500+
With this slower 166/333 FSB I can run PC3200 synchronously @ PC2700 speed, in dual-channel, with agressive memory timings.
At 200 FSB I always had some instability, but attributed it to the overclock.
Now I see that, like you, the instability probably comes from running the memory @ 400DDR dual-channel.
I have chosen the slower dual, but if you have a gen-u-wine XP3200+ @ 400FSB you sure don't wanna underclock your CPU...
So, glad to hear it's solid in single channel ;^)
Clearly you have already relaxed the timings (in your BIOS setup) as much as possible, trying to make it run dual...?
Only SPD is appropriate for these setup timings, unfortunately.
I believe you could achieve full PC3200 dual-channel operation if you purchased big-$ name-brand memory, matched in a dual-channel kit.
This memory would have very good numbers/low latencies, like the stuff I described at the start of this thread, but should still be run very loose (ie. SPD).
Since you seem to already have 3 sticks x 512MB generic PC3200, this advice probably pleases you not at all... :^(
But I offer it anyway.
So flash your very latest BIOS and loosen your timings to SPD-only, ideally finding 2 chips reporting the identical SPD, and you may achieve dual-channel @ 400DDR.
Otherwise it's Corsair / OCZ etc. for you - if you want the 6,200 MB/s memory bandwidth badly enough (hell, I'm strugglin' along at 2,700 dual = 5,400 MB/s here, myself :^) but not an option for you.
Hey man, we both need Athlon64's on Socket939, with integrated high-speed dual-channel memory control!! Solve all our problems... LoL
Regards

 

cheers for your help mr OGS,
I'm a bit reluctant to flash my bios, is this not a bit dodgy? currently got 1008 and the later versions don't seem to address the problem I have.
But I did think about relaxing the memory timings, at the moment they're:

CAS lat. 3.0
RAStoCAS. 3
RAS pre. 3
cycle. 8

Is it just the cycle time I need to increase? I don't know much about this sort of thing, but I s'pose one positive thing to come out of all this grief is that I'm starting to learn about this stuff.

I had only ordered 2 dimms, but a replacement was sent when I first thought one was knackered. Fortunately a mate wants my spare dimm, so its not too bad really.

cheers.

 

Yes, those 512's of PC3200 would not lie around collecting dust HERE I can tell you... LoL, they could power up 3 PCs, since 512MB is plenty for most people who are Undemanding Users :^)
Re: BIOS
Flashing it is no biggie - but you better take it seriously, and follow mfg. instructions carefully.
Technically your power supply should be uninterruptable whilst flashing, but WTF, what are the odds your electric will flicker or cut out during the flash? Slim.
Re: Memory timings
My ABit BIOS offers handy 'presets' for the timings, calling them SPD / Optimal / Aggressive / Turbo / Expert (expert being full-manual control).
All settings squeeze the timings a little more; for example when I run the PC3200 @ 333 I can set aggressive or turbo timings (which are not stable at the full PC3200 400MHz).
SPD, in any event, is the full-wimpy guaranteed-to-work setting that you should use when trying to achieve stability.
Yes your 3-3-3-8 looks pretty moderate, certainly not too pushed.
CPU-Z reports my SPD setting gives me 2.5-4-4-8
The more aggressive presets will squeeze this to 2.5-3-3-7 and Turbo I think attempts to deliver 2-3-3-5 or somesuch!
So try SPD if you have it, or something really loose like 3-4-4-8 if you have no choice but to set things manually.
L8R

 

I have noticed the following on my system playing with dual channel and 400mhz RAM;

AMD 3200+ cpu (400mhz FSB)
ASUS A7n8x-e mobo (latest bios 1013)
Crucial PC3200 DDR400 CLS=3

The ASUS mobo has 3 slots, 2 of which are for dual DDR RAM. When I stick in the Crucial memory, and run it with default settings, the machine hangs while POSTing.

After much ginning around, I found out;
- both memory sticks test fine with Memtest
- machine runs fine with single stick at 400mhz
- only way to get dual channel config is to drop memory timing (works at 83%, 166mhz (333 DDR).

Am going to continue playing with it and would appreciate any other feedback on similar experience.

It kinda sux, as I was thinking that the crucial ram should be reasonable.

I am considering returning the RAM and upgrading it to a better brand, but is this just as likely to have problems?

 

Hi Andycon,
It's true, dual-channel has the potential to introduce instability in certain circumstances.
If running the RAM PC3200 (400DDR) speed, you must run it loose, at SPD timings only!
If you have gotten your latest BIOS, and run the RAM @ SPD setting (hopefully both sticks indentical = SPD reporting same thing) then that's pretty well all you can do.
If you have a good power-supply and good cooling, these will help.
Try goosing the RAM voltage - just a 10th, one lousy 10th of a volt won't melt-down your rig and it might, combined with the loose (SPD) timings, solve your problem.
L8R

 

FYI, I bumped the RAM voltage a touch (running at SPD) and it seems to have done the trick. System running stable and staying cool(ish).

Many thanks for the ideas. At least now it's running as it should be.