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Topic Title: Anyone else with revE Opty do 4x512 @ 1T?
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Created On: 08/06/2005 01:30 PM
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 08/06/2005 01:30 PM
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HanShot1st
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I have discovered that my Opty's memory controller defaults to 1T command rate even when I have 4 double sided sticks filling my dimms. This is a rev E4 252, on a SK8V with 1003.008 beta bios. It is totally stable @ 1T.

It is known that current Venice and S.Diego cores cannot do this. But here we have an Opteron doing it and I'm wondering why.

Anyone else with a new rev. E chips running 4 double sided sticks @ 1T? My board won't even boot at 2T even when I force the setting in BIOS.

PLease help me figure out what's going here, cause I think if the new chips can all run 1T with lots of sticks, people would want to know that. Currently I can only speak for myself, but I got it working on my board easily.


' ">http://img331.imageshack.us/my...?image=verified0xr.jpg' ">http://img331.imageshack.us/my.php?image=32m1t6nc.jpg' ">http://img331.imageshack.us/my...ge=ddr450stable0ug.jpg' ">http://img331.imageshack.us/my...ge=ddr460stable9rl.jpg
 08/07/2005 06:46 AM
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Greyhound
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The '2T Timing' bit is not used with registered memory.

Generally, all those issues with running four DIMMs at DDR400-speeds are pretty much non-existent on the Socket 940-platform, except when all four sticks are double-sided. Registered memory may impose a slight performance-penalty, but it ensures stability even at high DRAM loadings (i.e. four sticks, or up to eight if running at DDR333-speeds).

Also, Socket 940 motherboards generally have 6-layer, high-quality PCBs, so you don't have as many board-related limitations as on a Socket 939 platform either.

See this document' ">http://www.amd.com/us-en/asset...nd_tech_docs/26094.PDF, section 3.5.11.1 (p. 109) and section 4.1.3.4 (p. 177f) for details on DRAM speed/loading with 940-pin parts.

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The opinions expressed above do not represent those of Advanced Micro Devices or any of their affiliates.

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 08/08/2005 03:20 AM
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HanShot1st
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QUOTE(Greyhound @ Aug 7 2005, 02:46 AM)The '2T Timing' bit is not used with registered memory.

Generally, all those issues with running four DIMMs at DDR400-speeds are pretty much non-existent on the Socket 940-platform, except when all four sticks are double-sided. Registered memory may impose a slight performance-penalty, but it ensures stability even at high DRAM loadings (i.e. four sticks, or up to eight if running at DDR333-speeds).

Also, Socket 940 motherboards generally have 6-layer, high-quality PCBs, so you don't have as many board-related limitations as on a Socket 939 platform either.

See this document' ">http://www.amd.com/us-en/asset...nd_tech_docs/26094.PDF, section 3.5.11.1 (p. 109) and section 4.1.3.4 (p. 177f) for details on DRAM speed/loading with 940-pin parts.
[right][snapback]475814[/snapback][/right]


Sorry don't have adobe installed to read that but I will,

I ask you though, if 2T timing isn't used with registered memory, then why does my S940 board have an option for it in the BIOS, and why can I easily switch back and forth between 1T and 2T in windows with software designed to do so?

All four of my sticks are double sided, running 4-way bank interleave at 1T cpc (command per clock). Trying to figure out if all rev. E opterons can do this, because venice and san diego cannot and must run 2T with more than 2 double sided sticks.




 08/08/2005 03:51 AM
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Greyhound
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QUOTEI ask you though, if 2T timing isn't used with registered memory, then why does my S940 board have an option for it in the BIOS, and why can I easily switch back and forth between 1T and 2T in windows with software designed to do so?
Well, you did notice that your board wouldn't even boot if you enabled the 2T-option in BIOS...
If you take a look at the appropriate datasheet/documentation (see above link), you'll notice that there is no 2T-option specified for 940-pin parts.

As for why the option is even present, my guess would be that being mainly a desktop-board manufacturer, Asus used a similar BIOS as in their desktop-offerings and just modified/optimized it for their Socket 940 board, leaving the 2T-option, even tho it's not really usable.
After all, there isn't that much of an architectural difference beween a Socket 940 and Socket 939 board and the chipset can be used on both platforms anyway.

Concerning the software-thing, I wouldn't be too sure that any software-adjustments you're making actually have a noticable effect at all...have you tried some benchmarks with different timing-options set via software?
QUOTEAll four of my sticks are double sided, running 4-way bank interleave at 1T cpc (command per clock). Trying to figure out if all rev. E opterons can do this, because venice and san diego cannot and must run 2T with more than 2 double sided sticks.

By specification, you shouldn't be able to do this (see the document I linked in my previous post)... /ph34r.gif' border='0' style='vertical-align:middle' alt='ph34r.gif' />

However, motherboard manufacturers do sometimes choose to allow configurations (especially concerning memory) that are feasible, but not officially supported by the processor or chipset.

A good example for this would be the fact that many motherboards based on the old VIA KT400-chipset did support running one or two sticks of memory at DDR400-speeds, even tho the chipset did not *officially* support this (despite the name) as official DDR400 support was added only with the KT400's successor, the KT400A.

-------------------------
The opinions expressed above do not represent those of Advanced Micro Devices or any of their affiliates.

<center><font color=red>MODERATOR</center></font>

AMD Athlon 64 X2 6000+ 89W :: Asus M2N32SLI Deluxe :: 2x1024MB Muskin XP2-6400 DDR2-800 :: BeQuiet! Darkpower Pro 530W :: 2x WD Raptor 74GB/10k rpm, RAID 0 :: ATI Radeon X1950XTX
 08/08/2005 04:07 PM
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HanShot1st
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QUOTE(Greyhound @ Aug 7 2005, 11:51 PM)Well, you did notice that your board wouldn't even boot if you enabled the 2T-option in BIOS...
If you take a look at the appropriate datasheet/documentation (see above link), you'll notice that there is no 2T-option specified for 940-pin parts.

As for why the option is even present, my guess would be that being mainly a desktop-board manufacturer, Asus used a similar BIOS as in their desktop-offerings and just modified/optimized it for their Socket 940 board, leaving the 2T-option, even tho it's not really usable.
After all, there isn't that much of an architectural difference beween a Socket 940 and Socket 939 board and the chipset can be used on both platforms anyway.

Concerning the software-thing, I wouldn't be too sure that any software-adjustments you're making actually have a noticable effect at all...have you tried some benchmarks with different timing-options set via software?

By specification, you shouldn't be able to do this (see the document I linked in my previous post)... /ph34r.gif' border='0' style='vertical-align:middle' alt='ph34r.gif' />

However, motherboard manufacturers do sometimes choose to allow configurations (especially concerning memory) that are feasible, but not officially supported by the processor or chipset.

A good example for this would be the fact that many motherboards based on the old VIA KT400-chipset did support running one or two sticks of memory at DDR400-speeds, even tho the chipset did not *officially* support this (despite the name) as official DDR400 support was added only with the KT400's successor, the KT400A.
[right][snapback]476425[/snapback][/right]


Of course I have run benchmarks between 1T and 2T with all four double sided sticks. BTW, Sandra incorrectly reports everything at 2T no matter what, which I believe is just a function of 4 sticks installed.

' ">http://img346.imageshack.us/my.php?image=1t0ju.jpg' ">http://img346.imageshack.us/my.php?image=2t2yo.jpg

follow this link for more complete benchmarking pics...
http://www.xtremesystems.org/f...showthread.php?t=70780' ">http://www.xtremesystems.org/f...showthread.php?t=70780
 08/08/2005 04:19 PM
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HanShot1st
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So can someone please with an new rev. E opty, with more than 2 double sided sticks, please download either A64Tweaker or Central Brain ID and tell me what it reports for command rate please.

Links

http://www.akiba-pc.com/download.php?view.40' ">http://www.akiba-pc.com/download.php?view.40 A64 Tweaker

http://cbid.amdclub.ru/' ">http://cbid.amdclub.ru/ version 750 is what I use...

Also, if you have either a 1x or 2x 252 rig please download this

http://www.thecoolest.zerobrai...idde.../A64MaxTemp.zip' ">http://www.thecoolest.zerobrai...n_Stuff/A64MaxTemp.zip

and report your revision, for example SH8-E4, and most importantly your max case temperature. Someone at another forum is compiling a database. For some reason he is looking specifically for Opteron 252s. Help if you can. Whatver you post here, I will post there. Thanks.

You can just post the screen shot like this too if you want.
' ">http://imageshack.us
 08/08/2005 11:38 PM
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HanShot1st
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Greyhound, according to page 117, 2T "should only be set with unbuffered dimms..."

So that I understand, and it then would explain why the board won't boot with 2t no matter, which you pointed out. /blush.gif' border='0' style='vertical-align:middle' alt='blush.gif' />

Reading that stuff makes me have more questions, lol.

This may sound like a funny question but do s940 chipsets run a memory divider on some of the dimms independent of the memory controller, while running a full ddr400 overall memory speed?

This whole 1T, 2T thing has really made me realize how little I understand about s940 memory architecture. /wacko.gif' border='0' style='vertical-align:middle' alt='wacko.gif' /> Doesnt help that I read about s939 stuff all day... hehe

But now I finally understand-registered memory=1T command rate always, regardless of dimms populated.



/smile.gif' border='0' style='vertical-align:middle' alt='smile.gif' />
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