GamePC and the nForce Twinbank/Superstability controversy

[GreenLantern]

There seems to be conflicting info out there about this nForce Twinbank/Superstability controversy.

GamePC's article, nForce Superstability - Feature or Bug Fix?, is the only article I've seen that attempts to explain the memory hit the MSI K7N 420D Pro takes when Slot 2 is used.
But there is a contradiction in the article:
At the beginning of the article he states:

<< When straying from nVidia's memory compatability and configuration listings, problems may start to manifest themselves. Keep in mind, if you follow these lists, the problems that occur on the following pages do not apply to you. nVidia has made it quite clear to us, that this issue only occurs when you stray from the specified memory lists available from MSI and nVidia. >>

Then when you get down to the tests he states:

<< For the memory, we used standard, run of the mill Crucial/Micron PC-2100 DDR SDRAM (Non-ECC, Non-Registered). >>

Well that memory module is on nVidia's compatibility list so why is this testbed experiencing the problem?

Then he says:

<< Turns out, the problem is that when you use dual-sided memory the second slot (slot B) of the second DDR memory bank of any given nForce motherboard, and you will consistently see a 20-25% drop in memory performance. >>

But nowhere does he mention how he came to this conclusion or why that would be a problem - just flatly blames double-sided ram.

nVidia's technical briefs on the nForce's technology and TwinBank implementation doesn't mention anything about Superstability which I find suspect.:disgust:
NSF4 mentioned Overclockers.com's review of MSI's K7N420 Pro as another experiencing this memory issue. He's using 2 identical 256MB sticks of NANYA-chipped Apacer PC2100 CAS2 for testing. So he has "strayed" from the list, so according to GamePC, that explains (albeit in another blackbox kind of way) why he's getting the performance hits.

I've got 3 sticks of Crucial PC2100 DDR SDRAM that I got for $30 each a couple of months ago. They are listed on nVidia's compatibility list. That hurdles one stumbling block: 1) not activating SS and lowering the FSB rate. The only setback I can see with "compatible" memory modules is the other issue I haven't talked about yet: 2) the twinBank arrangement limits how much memory is transferred at 128 bit and how much by 64 bit. The bank with the least amount of total memory dictates how much from each channel will be 128bit and the rest at 64bit.

So I'll have 2x256 delivering at 128bit and 256 at 64bit and all at 266MHz.

 

[NFS4]

NVIDIA didn't even ACKNOWLEDGE the SS issue publicy until GamePC came to them about it, so I it's not to surprising to see that NVIDIA wouldn't have mentioned anywhere in their tech docmuents.

SS sounds like something that marketing came up at the 11th hour

 

[GreenLantern]

<< SS sounds like something that marketing came up at the 11th hour >>

true, true.

Crucial is no longer on nVidia's nForce Compatibility List!!! Can anyone verify that the saw it there before - 'cause it ain't there now! I pulled out my ram and checked the module numbers and everything. No way I was dreaming.:Q:disgust:

 

[Gstanfor]

Another interesting article on the subject of Twinbank amdworld

Greg

 

[chrisconnolly]

Yes, the Crucial/Micron memory (the popular stuff) IS on nVidia's compatability listings. What it's NOT on is their DIMM compatability list.

Basically, nVidia certifies that the basic memory works in nForce, but it doesn't work in all three DIMM slots without having to be clocked down. I had a rather fun little conversation with nVidia about this, and how confusing it was not only to myself, but to users out there trying to find out if their DDR is certified. Apparently they're going to try and work on this in the future, to help eliminate the confusion.

It's certainly a very confusing topic, but if anyone has any questions on it, feel free to email me.

- Chris / GamePC

 

[GreenLantern]

<< Yes, the Crucial/Micron memory (the popular stuff) IS on nVidia's compatability listings. What it's NOT on is their DIMM compatability list. >>

Crucial/Micron memory = DIMM. (?)
What list are you looking at?

I've got CT3264Z265.16T Crucial PC2100 DDR DIMMS. Crucial is compatible but their DIMM's aren't? Come again?

 

[GreenLantern]

For interest's sake:
This is from MSI's K7N420Pro Mobo Manual. Confusing?

Appendix: DDR DIMM Configuration
Configuration Rules
Observe the following rules when configuring DDR DIMMs:
1. Follow correct DIMM installation order. DIMMs must be populated
consecutively, in order, starting with the DIMM1 socket.
2. Do not populate DIMM3 socket with any dual load (dual bank) modules (for BIOS
ver. 210 or later version).
*Do not populate DIMM2 socket with any dual load (dual bank) modules (for BIOS
ver. 200).
Note: Dual load refers to physical device beds on the data bus
Note: For best performance on 128bit system, we recommend you to use the same
DDR DIMM for both slots.

 

[chrisconnolly]

Unless they've changed it (which they may have), I believe most of the standard Crucial PC-2100 DDR DIMMS are supported by nVidia.

The thing here is that nVidia validates the memory to work with nForce, but only in two DIMM slots. Even if the memory is nVidia approved, if it's double-sided, it will NOT function at full speed when used in all three slots. It's an inherent issue with nForce, and I have yet to see a single double-sided DDR module be functional at full-speed in all three DIMM slots.

Interestingly enough, I'm just looking at Abit's nForce motherboard, which only has two DIMM slots, thus alleviating the Superstability issue.

- Chris / GamePC

 

[Gstanfor]

Hmmm...

The current bios for download is 2.00, so there must be a new version of the bios (V2.10) about to be released.

Greg

 

[chrisconnolly]

Yes, both MSI and nVidia told me that a new BIOS for the MSI K7N420 will make things even more confusing.

With BIOS 2.0 (shipping), the DIMM slot to avoid is DIMM 2.

With the new BIOS (2.1+), they've changed the memory addressing, so DIMM 3 will be the slot to avoid. Neither company gave me an ETA on when the BIOS will be released, but it will still not fix the Superstability issue, it simply changes the DIMM slot that it occurs in.

- Chris / GamePC

 

[Rogue]

Hmmm...this answers a big question for me then. Hold off on buying any nForce based board to use with my two identical sticks of 256MB Crucial DDR I bought when it was cheap just for this purpose. Thanks!

 

[Loba]

chrisconnolly i forgot to perform one last test on the nforce and that was using only dimm2 did u perform a test just on that bank populated.
also chris im using the 2.02 bios i got from a source dated 5/11/01 do want a copy if so just email the address.

brian...

ps it may be why we are seeing conflicting performance.but it does not cure the dimm populated theory.

http://www.amdworld.co.uk

 

[chrisconnolly]

Hi Loba :

Yes, we did do tests on DIMM2, as that's currently the slot that causes Superstability to kick in (when loaded with dual-sided memory module).

If you test outside of DIMM2, you won't see the effects of SS mode.

- Chris / GamePC

 

[Loba]

ok i see what your saying ,thanks and do u require the beta bios 2.02??

 

[GreenLantern]

So if I've got 3 sticks of CT3264Z265.16T Crucial PC2100 DDR ram, what is the best I could do with it?

 

[Adul]

get a tyan tiger and go dual proc?
or wiat for 760 MPX mb

 

[Rogue]

According to the Nvidia Compaibility list, my memory I bought a few months ago is approved for use on the 220 platform, not the 420 platform. What exactly does that mean to me? Does that mean my memory is useless on the MSI board since it's 420 based or does that mean it will run slower or .... WFT does that mean?!