Registered Vs Unregistered DDR SDRAM

[gustavo]

Excuse me for the ignorance, what kind of DDR is supposed the MSI 6380 to support Registered or Unregistered ?

And what are the diffrences between them, is there a simple way of recognize the difference ?

I read somewhere that to populate the 3 slots you have to use registered, is that be true, I did not see anything about this at the manual.

Thanks Gustavo.-

[brad]

Registered and/or ECC memory has additional error checking that non-ECC and/or unregistered sticks don't have, and are generally a bit slower than unregistered memory for that reason. Registered memory is, for the most part, intended for use in servers.

You're right, MSI didn't do us many favors in the 6380 manual when it comes to memory. I have three sticks of registered 512 Mb PC2100 in my K7T266 Pro2 UNIX machine and found that yes, all three had to be registered to use all three slots. Fails POST otherwise.

My windows 98-se box however has 2 sticks of 512 meg PC2100 and everything works fine. Attempting to put anything, registered or not in the third slot fails. This appears to indicate that the conclusions you have read elsewhere are correct. This is not on just MSI's boards, applies to all KT266A based boards as well.

Glad you brought this up. I need to scrounge around for info on this that is more official than just home-grown observations. May be hard to do however because VIA is hardly very forthcomming with this kind of info.

Brad

[gustavo]

Brad: how do I know if a stick od DDR SDRAM is registered, have to ask the manufacturer or there is any visible way of recognizing the difference ??

And guess maybe you dont have the "home-grown observations"
but do you think the need for registered to populate the 3 slots applies to KT266 based boards (as my MSI K7T266 PRO) ?

Many thanks Brad, appreciate very much your help.

Gustavo.-

[brad]

The only way I know of to tell the difference visually is that on a registered DIMM there will be one or more very small multi-pin chips that unregistered DIMMs don't have.

And yes, as you have read elsewhere, and as I have found on my own, registered DIMMs are required to populate all three slots on KT266 and KT266A based boards.

I'm slowly finding some official info on this subject and will post an advisory or something like that with links right here when and if I can get it all put together properly.

Brad

[brad]

Gustavo,

According to official VIA documentation, the KT266A does indeed support ECC as well as registered DDR modules, so some of the BS you may have read elsewhere regarding this is a load of crap. There is no substitute for getting official docs so here's the link to VIA's official KT266A whitepaper in PDF format, which covers this very well:

http://www.viatech.com/en/apollo/KT266A_WhitePaper.pdf

That file states that it also supports standard PC100 and PC133 modules, although the design of the motherboard may preclude that, and it appears that most KT266A boards have done exactly that. Frankly though, I can't understand why anyone would want to not use DDR SDRAM except as a cost saving measure. With memory prices as they are now it makes no sense at all to not go DDR.

I'm still looking for more MSI specific info and will post it here as I find it but that will give you something official to go with for now.

Brad

[brad]

Well I must now correct one of my previous statements. I said that registered DIMMS were required to use all three DIMM slots but have just found an exception to that apparent rule on one of my own K7T266A Pro2 boards, and I have read of others as well.

Just for grins, I tried three sticks of UNREGISTERED 256 Meg PC2100 and it works fine, even with agressive memory timing settings. These are also "generics" so the plot thickens. Makes me wonder if the size of the unregistered sticks has anything to do with it but I don't have three unregistered 512 Meg PC2100 sticks to find out.

Also makes me wonder if it has anything at all to do with why so many people have had problems using the 133 FSB but I just don't know. Never even seen that alledged problem on 18 of these boards, and 11 of them have 1800XP processors.

Brad

[gustavo]

First dont get what you mean by

"According to official VIA documentation, the KT266A does indeed support ECC as well as registered DDR modules, so some of the BS you may have read elsewhere regarding this is a load of crap. "

The only thing I read was the suggestion that to populate the 3 slots you have to use registered DDR SDRAM, nothing about its not supporting registered modules, I still dont know if mine is or not registered the only thing I know is that the chips on the stick are labeled "SAMSUNG K4 H2 808 38C-TCB0" and are the only you can get here in my country (Uruguay), as I have just 1 stick 256 MB) was planning to buy another one and on the future the third I got worried and there is no technical support having enough knowledge here so you buy what is in stock or dont buy anything, I wanted the MSI K7T266 PRO2 as you recommended me one thread some months ago but the latest state of the art here is the version with the VIA KT266 chipset so I shall be very happy having one.

Second regarding the problem in itself (if registered DIMMS are required to populate all three DIMM slots) I guess you are also confused here and the idea is getting official documentation and support for anybody interested that reads this thread, I take it this way at least and will keep visiting it to see if you get something, will meanwhile stay with my 256 stick and wait to buy more.

No words are enough to thank you Brad, just I am thinking you are a kind of Gandhi or Jesus or Robin Hood or the like for helping people as you do.

Thanks anyway with all my strenght.
Gustavo.-

[brad]

You're welcome, and I am sorry that I keep forgetting that I need to be more carefull about how I say something in a reply. You are a very smart guy because you see the inconsistencies in what memory setups people say works and want to know why instead of assuming that duplicating what worked for someone else with a different brand mobo will work for you. We have both read enough to know that is a foolish assumption.

All I was trying to say in the other post you quoted is that VIA does say that registered DDR SDRAM modules are supported, but it DOES NOT say they are required when using more than 2 DIMM slots.

People need to be carefull about what they say when asked about this because many of them make it sound like it is a chipset rule when they have nothing to prove it. The inconsistencies alone strongly suggest that is more likely the motherboard design and memory module design, and I thank you for giving me a reason to check into it more because it reinforces some of the points I have made. Perhaps the most important points for you to keep in mind are:

1 - I have not seen a case on 18 K7T266 Pro2 boards where three sticks of registered memory totaling 256 or more megs did not work.

2 - I have seen cases where certain sets of 3 unregistered memory modules worked while another brand did not, regardless of total capacity, but using just 2 of them always worked.

3 - This happens on several KT266 boards, not just MSI's. Only the specific details of the inconsistencies vary.

Now as to how much memory to use, 256 megs should be enough but I think 512 megs is max for win98, win98-se and I think win-me without running into a few windows related problems. Chances are your 256 meg stick is not registered so getting another one should not cause any problem. If you do run into a problem, then it is more likely that one stick is bad, or that one is registered and the other is not. Just try to have 2 identical sticks.

I don't know anything about win2k or win-xp.

Hope that helps.....

Brad

[gustavo]

Brad, you that owned both systems, have really noticed any difference between the VIA Kt266 Vs the Kt266A, if so is a big difference ??

Just curious, is that it seems so much marketing reading the whitepapers......

[brad]

I have never had a KT266 based board. I have two of MSI's K7T266 Pro2 systems now. There is no big difference in performance as far as what you can see or feel. You will have to run benchmarks to see the difference, and that is almost entirely in memory performance.

Brad