Latest Athlon 64 product introductions

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Archived from groups: comp.sys.ibm.pc.hardware.chips,comp.sys.intel (More info?)

Rupert Pigott wrote:

> KR Williams wrote:
>
>> In article <8libc09361ibdvdja5icpc9s952hq4eefi@4ax.com>,
>> nospam@email.com says...
>>
>>> On Thu, 03 Jun 2004 18:07:42 GMT, "Yousuf Khan" <bbbl67@ezrs.com> wrote:
>>>
>>>
>>>> Later AMD decided that it would like Athlon 64 systems to be
>>>> dual-channel
>>>> too like the Opterons, but it didn't want them to use the expensive
>>>> buffered
>>>> RAM like the Opterons. So Socket 939 was born -- dual-channel,
>>>> unbuffered
>>>> DDR RAM.
>>>
>>>
>>> 939 boards are also cheaper to make, 4 layer instead of 6.
>>
>>
>>
>> Why? I don't see the memory differences as significant.
>
>
> Same question crossed my mind. My guess is that they weren't *too*
> bothered about Opteron boards being costly so they didn't put much
> effort into keeping the layer count down. I'll bet that some bright
> spark spotted an alternative pin-out that would allow 4 layer
> boards sometime after S940 was released, hence the magic new S939
> that allows 4-Layer boards.
>

No. Socket 940, 939, and 754 were all announced at the same time.
Manufacturers were ready to start cranking out Socket 939 boards
more than a year ago but AMD just wasn't producing the chips.

As well, PDF illustrating the pin-outs for all three sockets were
available at AMD's site early last year and I would expect they
are still there if you are interested.

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips,comp.sys.intel (More info?)

Yousuf Khan wrote:

> KR Williams <krw@att.biz> wrote:
>> In article <19nxc.118693$Ar.81900
>> @twister01.bloor.is.net.cable.rogers.com>, bbbl67@ezrs.com
>> says...
>>> Ed <uranidiot@behappy.com> wrote:
>>>> On Tue, 08 Jun 2004 16:37:02 +0200, Grumble <a@b.c> wrote:
>>>>
>>>>> Ed wrote:
>>>>>> 939 boards are also cheaper to make, 4 layer instead of 6.
>>>>>
>>>>> Can somebody explain why socket 754 motherboards needed two
>>>>> more layers?
>>>>
>>>>
>>>> 940 is 6
>>>> 754 are 4 layer isn't it?
>>>
>>> Oh geez, now we got two Ed's, and they're gonna carry on a
>>> confusing debate amongst themselves. 🙂
>>
>> Nope. Same Ed, just a different moniker (look at the headings).
>
> If they are the same Ed, then why is one asking a question of the
> other?

My news server has a "Grumble" post threaded in between.

> This has the potential of making the Tony vs. Tony Hill
> debates look comprehensible.

;-) That one got me!

--
Keith

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips,comp.sys.intel (More info?)

Rupert Pigott wrote:

> KR Williams wrote:
>> In article <8libc09361ibdvdja5icpc9s952hq4eefi@4ax.com>,
>> nospam@email.com says...
>>
>>>On Thu, 03 Jun 2004 18:07:42 GMT, "Yousuf Khan" <bbbl67@ezrs.com>
>>>wrote:
>>>
>>>
>>>>Later AMD decided that it would like Athlon 64 systems to be
>>>>dual-channel too like the Opterons, but it didn't want them to
>>>>use the expensive buffered RAM like the Opterons. So Socket 939
>>>>was born -- dual-channel, unbuffered DDR RAM.
>>>
>>>939 boards are also cheaper to make, 4 layer instead of 6.
>>
>>
>> Why? I don't see the memory differences as significant.
>
> Same question crossed my mind. My guess is that they weren't *too*
> bothered about Opteron boards being costly so they didn't put much
> effort into keeping the layer count down. I'll bet that some
> bright spark spotted an alternative pin-out that would allow 4
> layer boards sometime after S940 was released, hence the magic new
> S939 that allows 4-Layer boards.

The only possible difference I can see is that the S939 boards won't
be pretending to do more than one processor, so may be somewhat
simpler that way. However that would assume the HT links aren't
being used for anything else. So why all the pins?

--
Keith

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips,comp.sys.intel (More info?)

Rob Stow wrote:
> Rupert Pigott wrote:
>
>> KR Williams wrote:
>>
>>> In article <8libc09361ibdvdja5icpc9s952hq4eefi@4ax.com>,
>>> nospam@email.com says...
>>>
>>>> On Thu, 03 Jun 2004 18:07:42 GMT, "Yousuf Khan" <bbbl67@ezrs.com>
>>>> wrote:
>>>>
>>>>
>>>>> Later AMD decided that it would like Athlon 64 systems to be
>>>>> dual-channel
>>>>> too like the Opterons, but it didn't want them to use the expensive
>>>>> buffered
>>>>> RAM like the Opterons. So Socket 939 was born -- dual-channel,
>>>>> unbuffered
>>>>> DDR RAM.
>>>>
>>>>
>>>>
>>>> 939 boards are also cheaper to make, 4 layer instead of 6.
>>>
>>>
>>>
>>>
>>> Why? I don't see the memory differences as significant.
>>
>>
>>
>> Same question crossed my mind. My guess is that they weren't *too*
>> bothered about Opteron boards being costly so they didn't put much
>> effort into keeping the layer count down. I'll bet that some bright
>> spark spotted an alternative pin-out that would allow 4 layer
>> boards sometime after S940 was released, hence the magic new S939
>> that allows 4-Layer boards.
>>
>
> No. Socket 940, 939, and 754 were all announced at the same time.
> Manufacturers were ready to start cranking out Socket 939 boards
> more than a year ago but AMD just wasn't producing the chips.

Eeek, I hadn't twigged 939 & 940 were launched at the same time. Seems
a bit odd that the 4/6 layer difference exists in that case.

> As well, PDF illustrating the pin-outs for all three sockets were
> available at AMD's site early last year and I would expect they
> are still there if you are interested.

Must admit I'm curious to see what kind of differences exist between 939
and 940.

Thanks,
Rupert

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips,comp.sys.intel (More info?)

Bitstring <1086792271.200887@teapot.planet.gong>, from the wonderful
person Rupert Pigott <roo@try-removing-this.darkboong.demon.co.uk> said
<snip>
>>>939 boards are also cheaper to make, 4 layer instead of 6.

>> Why? I don't see the memory differences as significant.
>
>Same question crossed my mind. My guess is that they weren't *too*
>bothered about Opteron boards being costly so they didn't put much
>effort into keeping the layer count down. I'll bet that some bright
>spark spotted an alternative pin-out that would allow 4 layer
>boards sometime after S940 was released, hence the magic new S939
>that allows 4-Layer boards.

I'm not sure you can blame the pinout - I can't see why you can't route
anything with 4 layers (actually, iirc, with 2 .. in theory, for
constant width wires), unless/until you start needing massive power
distribution and ground planes?

--
GSV Three Minds in a Can
Outgoing Msgs are Turing Tested,and indistinguishable from human typing.

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips,comp.sys.intel (More info?)

GSV Three Minds in a Can wrote:

> Bitstring <1086792271.200887@teapot.planet.gong>, from the
> wonderful person Rupert Pigott
> <roo@try-removing-this.darkboong.demon.co.uk> said <snip>
>>>>939 boards are also cheaper to make, 4 layer instead of 6.
>
>>> Why? I don't see the memory differences as significant.
>>
>>Same question crossed my mind. My guess is that they weren't *too*
>>bothered about Opteron boards being costly so they didn't put much
>>effort into keeping the layer count down. I'll bet that some
>>bright spark spotted an alternative pin-out that would allow 4
>>layer boards sometime after S940 was released, hence the magic new
>>S939 that allows 4-Layer boards.
>
> I'm not sure you can blame the pinout - I can't see why you can't
> route anything with 4 layers (actually, iirc, with 2 .. in theory,
> for constant width wires), unless/until you start needing massive
> power distribution and ground planes?

Read that last sentence again. ;-)

The reality is that you need the ground/power planes for electrical
reasons, other than the *MASSIVE* power these things dissipate.
Think about 60W at ~1.25V. That's a wee bit of current. In
addition the impedance of the power distribution must be kept as
low as possible to reduce noise. The planes are also necessary to
keep the impedance of the signal lines constant. Two of the four
planes were power planes in the 486 days, without the massive
currents we now see. Thus, a four-layer board has only two wiring
planes, which are normally wired horizontally and vertically.
"Manhattan" wiring (streets on one side, avenues on the other) to
hook everything together.

Yes, you can theoretically wire anything using two layers, with an
infinite wiring space, infinitely long wires, and an infinite
number of vias. To make everything work, there are restrictions on
all of these as well as the differences in these from one wire to
another.

--
Keith

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips,comp.sys.intel (More info?)

Rupert Pigott <roo@try-removing-this.darkboong.demon.co.uk> wrote:
> Must admit I'm curious to see what kind of differences exist between
> 939 and 940.

From a purely end-user perspective, the biggest difference between 939 and
940 is that 939 is for unbuffered DDR, while 940 is for server-class
buffered DDR. I assume that since 940 uses buffered DDR, the potential
exists to outfit 940 board with well over two DIMMs per processor.

Yousuf Khan

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips,comp.sys.intel (More info?)

Yousuf Khan wrote:

> Rupert Pigott <roo@try-removing-this.darkboong.demon.co.uk> wrote:
>> Must admit I'm curious to see what kind of differences exist
>> between 939 and 940.
>
> From a purely end-user perspective, the biggest difference between
> 939 and 940 is that 939 is for unbuffered DDR, while 940 is for
> server-class buffered DDR. I assume that since 940 uses buffered
> DDR, the potential exists to outfit 940 board with well over two
> DIMMs per processor.

But, but... Why would a 940 board that *only* supports four DIMMs
be more complicated than a 939 board that only supports 4 DIMMs?
DIMMs is Dimms (at least on this level).

--
Keith

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

Bitstring <3oadnSFRhc3F6FrdRVn-vA@adelphia.com>, from the wonderful
person K Williams <krw@adelphia.net> said
>GSV Three Minds in a Can wrote:
>
>> Bitstring <1086792271.200887@teapot.planet.gong>, from the
>> wonderful person Rupert Pigott
>> <roo@try-removing-this.darkboong.demon.co.uk> said <snip>
>>>>>939 boards are also cheaper to make, 4 layer instead of 6.
>>
>>>> Why? I don't see the memory differences as significant.
>>>
>>>Same question crossed my mind. My guess is that they weren't *too*
>>>bothered about Opteron boards being costly so they didn't put much
>>>effort into keeping the layer count down. I'll bet that some
>>>bright spark spotted an alternative pin-out that would allow 4
>>>layer boards sometime after S940 was released, hence the magic new
>>>S939 that allows 4-Layer boards.
>>
>> I'm not sure you can blame the pinout - I can't see why you can't
>> route anything with 4 layers (actually, iirc, with 2 .. in theory,
>> for constant width wires), unless/until you start needing massive
>> power distribution and ground planes?
>
>Read that last sentence again. ;-)
>
>The reality is that you need the ground/power planes for electrical
>reasons, other than the *MASSIVE* power these things dissipate.
>Think about 60W at ~1.25V. That's a wee bit of current. In
>addition the impedance of the power distribution must be kept as
>low as possible to reduce noise. The planes are also necessary to
>keep the impedance of the signal lines constant. Two of the four
>planes were power planes in the 486 days, without the massive
>currents we now see.

>Yes, you can theoretically wire anything using two layers, with an
>infinite wiring space, infinitely long wires, and an infinite
>number of vias. To make everything work, there are restrictions on
>all of these as well as the differences in these from one wire to
>another.

Yes I know .. I spent 20 years working on / managing IC CAD software,
including routers, and I haven't quiet forgotten all of it yet. 8>.

You still haven't explained to my satisfaction why a =pin-out change=
can suddenly force the requirement for another two wiring planes. I can
see why an =additional= power requirement, or need for =additional=
signal conditioning (like you're running on the hairy edge, which is why
you needed buffered DIMMS in the first place) could up the wiring planes
needed, but a pinout change which magically needs two extra board layers
seems like something you could hardly devise if you worked at it.

--
GSV Three Minds in a Can
Outgoing Msgs are Turing Tested,and indistinguishable from human typing.

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

GSV Three Minds in a Can wrote:

> Bitstring <3oadnSFRhc3F6FrdRVn-vA@adelphia.com>, from the
> wonderful person K Williams <krw@adelphia.net> said
>>GSV Three Minds in a Can wrote:
>>
>>> Bitstring <1086792271.200887@teapot.planet.gong>, from the
>>> wonderful person Rupert Pigott
>>> <roo@try-removing-this.darkboong.demon.co.uk> said <snip>
>>>>>>939 boards are also cheaper to make, 4 layer instead of 6.
>>>
>>>>> Why? I don't see the memory differences as significant.
>>>>
>>>>Same question crossed my mind. My guess is that they weren't
>>>>*too* bothered about Opteron boards being costly so they didn't
>>>>put much effort into keeping the layer count down. I'll bet that
>>>>some bright spark spotted an alternative pin-out that would
>>>>allow 4 layer boards sometime after S940 was released, hence the
>>>>magic new S939 that allows 4-Layer boards.
>>>
>>> I'm not sure you can blame the pinout - I can't see why you
>>> can't route anything with 4 layers (actually, iirc, with 2 .. in
>>> theory, for constant width wires), unless/until you start
>>> needing massive power distribution and ground planes?
>>
>>Read that last sentence again. ;-)
>>
>>The reality is that you need the ground/power planes for
>>electrical reasons, other than the *MASSIVE* power these things
>>dissipate.
>>Think about 60W at ~1.25V. That's a wee bit of current. In
>>addition the impedance of the power distribution must be kept as
>>low as possible to reduce noise. The planes are also necessary to
>>keep the impedance of the signal lines constant. Two of the four
>>planes were power planes in the 486 days, without the massive
>>currents we now see.
>
>>Yes, you can theoretically wire anything using two layers, with an
>>infinite wiring space, infinitely long wires, and an infinite
>>number of vias. To make everything work, there are restrictions
>>on all of these as well as the differences in these from one wire
>>to another.
>
> Yes I know .. I spent 20 years working on / managing IC CAD
> software, including routers, and I haven't quiet forgotten all of
> it yet. 8>.
>
> You still haven't explained to my satisfaction why a =pin-out
> change= can suddenly force the requirement for another two wiring
> planes.

Oh, my... We're now asking the same question! My proposal is that
there is no pretense of a MP system with S939, so things are
relaxed a bit. That supposes that a Uni-S940 should be do-able
w/4-layers too. Maybe no one wants to design a S940 board for a
uni? I find that hard to swallow too. so...

> I can see why an =additional= power requirement, or need
> for =additional= signal conditioning (like you're running on the
> hairy edge, which is why you needed buffered DIMMS in the first
> place) could up the wiring planes needed, but a pinout change
> which magically needs two extra board layers seems like something
> you could hardly devise if you worked at it.

Registered DIMMs should need *less* care in layout, given the same
number. That's sorta the purpose behind registering.

--
Keith

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips,comp.sys.intel (More info?)

Rupert Pigott wrote:

>> No. Socket 940, 939, and 754 were all announced at the same time.
>> Manufacturers were ready to start cranking out Socket 939 boards
>> more than a year ago but AMD just wasn't producing the chips.
>
>
> Eeek, I hadn't twigged 939 & 940 were launched at the same time. Seems
> a bit odd that the 4/6 layer difference exists in that case.

I saw my first Socket 939 board at the same time I saw my
first 940 board - in Feb 1993. At that time the AMD rep
at the demo was predicting general availability of socket
940 chips for April 2003 (which actually happened) and
socket 939 chips for Q3 2003. So far Q3 2004 is just a
few weeks away and no socket 939 chips seem to be in stock
in any stores.

(I also saw a 4-way board by NewiSys at that demo with
four 800 MHz Opties on it.🙂 )

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

K Williams wrote:

> Yousuf Khan wrote:
>
>
>>Rupert Pigott <roo@try-removing-this.darkboong.demon.co.uk> wrote:
>>
>>>Must admit I'm curious to see what kind of differences exist
>>>between 939 and 940.
>>
>>From a purely end-user perspective, the biggest difference between
>>939 and 940 is that 939 is for unbuffered DDR, while 940 is for
>>server-class buffered DDR. I assume that since 940 uses buffered
>>DDR, the potential exists to outfit 940 board with well over two
>>DIMMs per processor.
>
>
> But, but... Why would a 940 board that *only* supports four DIMMs
> be more complicated than a 939 board that only supports 4 DIMMs?
> DIMMs is Dimms (at least on this level).
>

There is nothing inherent in the Opty that limits motherboard
manufacturers to 4 DIMMs per processor. HP, for example, has
managed 8 in their 4-way systems.

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

K Williams <krw@adelphia.net> wrote:
> Yousuf Khan wrote:
>> From a purely end-user perspective, the biggest difference between
>> 939 and 940 is that 939 is for unbuffered DDR, while 940 is for
>> server-class buffered DDR. I assume that since 940 uses buffered
>> DDR, the potential exists to outfit 940 board with well over two
>> DIMMs per processor.
>
> But, but... Why would a 940 board that *only* supports four DIMMs
> be more complicated than a 939 board that only supports 4 DIMMs?
> DIMMs is Dimms (at least on this level).

Probably because a 940 board will truly be able to support 4 DIMMs whereas a
939 board will more than likely be limited to two DIMMs in reality. When was
the last time you saw desktop boards routinely support more than two DIMMs?
I can only remember this happening back in the Pentium 1 days. Ever since
then, all I've ever seen is warnings against putting any more than two DIMMs
on any board even if it has space for more.

The only ones that can truly do it these days are the buffered DIMMs on
server boards.

Yousuf Khan

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

K Williams <krw@adelphia.net> wrote:
>>>> Oh geez, now we got two Ed's, and they're gonna carry on a
>>>> confusing debate amongst themselves. 🙂
>>>
>>> Nope. Same Ed, just a different moniker (look at the headings).
>>
>> If they are the same Ed, then why is one asking a question of the
>> other?
>
> My news server has a "Grumble" post threaded in between.

Yes, so does mine.

But the first Ed was saying that a Socket 745 required six layer mobos,
while Socket 939 requires only 4 layer. Then Grumble asked Ed #1 why that is
the case? Then Ed #2 responded to Grumble by answering with a
semi-rhetorical question: he asked if it wasn't true that S745 actually
requires 4 layers while S939 requires 6 layers, therefore contradicting Ed
#1.

>> This has the potential of making the Tony vs. Tony Hill
>> debates look comprehensible.
>
> ;-) That one got me!

I think if this sort of thing happens more often, then people who are using
things like OE-Quotefix to format their news reader styles, make sure that
they include at least the email addresses in the quote header.

Yousuf Khan

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

K Williams <krw@adelphia.net> wrote:
> The only possible difference I can see is that the S939 boards won't
> be pretending to do more than one processor, so may be somewhat
> simpler that way. However that would assume the HT links aren't
> being used for anything else. So why all the pins?

Well as some people have pointed out in the case of Pentium 4's Socket
775 -- extra grounding.

Then again it's possible that maybe AMD is already preparing for DDR2, and
Socket 939 is a forward looking design preparing for that day.

Yousuf Khan

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips,comp.sys.intel (More info?)

Rob Stow <rob.stow@sasktel.net> wrote:
>> Eeek, I hadn't twigged 939 & 940 were launched at the same time.
>> Seems a bit odd that the 4/6 layer difference exists in that case.
>
> I saw my first Socket 939 board at the same time I saw my
> first 940 board - in Feb 1993. At that time the AMD rep
> at the demo was predicting general availability of socket
> 940 chips for April 2003 (which actually happened) and
> socket 939 chips for Q3 2003. So far Q3 2004 is just a
> few weeks away and no socket 939 chips seem to be in stock
> in any stores.

Well, that's some forward thinking on AMD's part, they were already prepared
with a 64-bit processor socket ten years before they released it. 🙂

Yousuf Khan

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips,comp.sys.intel (More info?)

Yousuf Khan wrote:

> Rob Stow <rob.stow@sasktel.net> wrote:
>
>>>Eeek, I hadn't twigged 939 & 940 were launched at the same time.
>>>Seems a bit odd that the 4/6 layer difference exists in that case.
>>
>>I saw my first Socket 939 board at the same time I saw my
>>first 940 board - in Feb 1993. At that time the AMD rep
>>at the demo was predicting general availability of socket
>>940 chips for April 2003 (which actually happened) and
>>socket 939 chips for Q3 2003. So far Q3 2004 is just a
>>few weeks away and no socket 939 chips seem to be in stock
>>in any stores.
>
>
> Well, that's some forward thinking on AMD's part, they were already prepared
> with a 64-bit processor socket ten years before they released it. 🙂
>
> Yousuf Khan
>
>

I meant last year. 2003, not 1993. 2004-1 = 1993 🙂
That has got to be the weirdest "typo" I've ever done.
Either that or my math qualifies me for a gov't job.

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

Yousuf Khan wrote:

> But the first Ed was saying that a Socket 745 required six layer
> mobos, while Socket 939 requires only 4 layer.

Just a nit. Socket 754, not 745.

Go ahead, count 'em 🙂

http://www.hardspell.com/newsimage/200392613445242585.jpg

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

Rob Stow wrote:

> K Williams wrote:
>
>> Yousuf Khan wrote:
>>
>>
>>>Rupert Pigott <roo@try-removing-this.darkboong.demon.co.uk>
>>>wrote:
>>>
>>>>Must admit I'm curious to see what kind of differences exist
>>>>between 939 and 940.
>>>
>>>From a purely end-user perspective, the biggest difference
>>>between 939 and 940 is that 939 is for unbuffered DDR, while 940
>>>is for server-class buffered DDR. I assume that since 940 uses
>>>buffered DDR, the potential exists to outfit 940 board with well
>>>over two DIMMs per processor.
>>
>>
>> But, but... Why would a 940 board that *only* supports four
>> DIMMs be more complicated than a 939 board that only supports 4
>> DIMMs? DIMMs is Dimms (at least on this level).
>>
>
> There is nothing inherent in the Opty that limits motherboard
> manufacturers to 4 DIMMs per processor. HP, for example, has
> managed 8 in their 4-way systems.

I didn't say there was. However many 940 boards only support four
(mine, fer instance😉. Why would a 940 board that only supported
four take any more wiring channels than a 939 board that supported
four? For that matter, once you've fanned the signals out to the
memory modules, why would more memory modules require more layers?
Both assuming dual-channel, of course.

--
Keith

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

Yousuf Khan wrote:

> K Williams <krw@adelphia.net> wrote:
>> Yousuf Khan wrote:
>>> From a purely end-user perspective, the biggest difference
>>> between 939 and 940 is that 939 is for unbuffered DDR, while 940
>>> is for server-class buffered DDR. I assume that since 940 uses
>>> buffered DDR, the potential exists to outfit 940 board with well
>>> over two DIMMs per processor.
>>
>> But, but... Why would a 940 board that *only* supports four
>> DIMMs be more complicated than a 939 board that only supports 4
>> DIMMs? DIMMs is Dimms (at least on this level).
>
> Probably because a 940 board will truly be able to support 4 DIMMs
> whereas a 939 board will more than likely be limited to two DIMMs
> in reality. When was the last time you saw desktop boards
> routinely support more than two DIMMs?

Lots of 'em support three. Remember, the 939 is still dual-channel
(right?). Are you suggesting that each channel will only have one
DIMM? Perhaps that's the only way to make it work, but I'm glad I
went with the 940, if so. Still once you've transformed the wires
out to the first DIMM, the traces to the second are pretty much
parallel, thus I still don't understand the issue.

> I can only remember this
> happening back in the Pentium 1 days. Ever since then, all I've
> ever seen is warnings against putting any more than two DIMMs on
> any board even if it has space for more.

Remember, It's dual channel, so there would only be two on each
channel (for a total of four).

> The only ones that can truly do it these days are the buffered
> DIMMs on server boards.

Sure at these speeds, and two per channel.

We're still missing something here.

--
Keith

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

Yousuf Khan wrote:

> K Williams <krw@adelphia.net> wrote:
>> The only possible difference I can see is that the S939 boards
>> won't be pretending to do more than one processor, so may be
>> somewhat
>> simpler that way. However that would assume the HT links aren't
>> being used for anything else. So why all the pins?
>
> Well as some people have pointed out in the case of Pentium 4's
> Socket 775 -- extra grounding.

....and the 940 doesn't need 'em. I'm not buying that one either.

> Then again it's possible that maybe AMD is already preparing for
> DDR2, and Socket 939 is a forward looking design preparing for
> that day.

Perhaps. But why wouldn't they build that into the 940 footprint
too? Leave the desktop with faster memory (down the road, of
course) than the "server" chipset?

--
Keith

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

K Williams <krw@adelphia.net> wrote:
> Yousuf Khan wrote:
>> Probably because a 940 board will truly be able to support 4 DIMMs
>> whereas a 939 board will more than likely be limited to two DIMMs
>> in reality. When was the last time you saw desktop boards
>> routinely support more than two DIMMs?
>
> Lots of 'em support three. Remember, the 939 is still dual-channel
> (right?). Are you suggesting that each channel will only have one
> DIMM? Perhaps that's the only way to make it work, but I'm glad I
> went with the 940, if so. Still once you've transformed the wires
> out to the first DIMM, the traces to the second are pretty much
> parallel, thus I still don't understand the issue.

Well, it's a dual-channel in the sense that the processor reads the lower
64-bits from the first DIMM and the upper 64-bits from the second DIMM. I
don't think it actually puts the two chips in separate banks and does bank
interleaving in the traditional dual-channel sense. This is how Pentium 4's
dual-channel works as well.

Yousuf Khan

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

K Williams <krw@adelphia.net> wrote:
> Yousuf Khan wrote:
>> Well as some people have pointed out in the case of Pentium 4's
>> Socket 775 -- extra grounding.
>
> ...and the 940 doesn't need 'em. I'm not buying that one either.

Well, I don't either, just passing on what's been stated elsewhere.

>> Then again it's possible that maybe AMD is already preparing for
>> DDR2, and Socket 939 is a forward looking design preparing for
>> that day.
>
> Perhaps. But why wouldn't they build that into the 940 footprint
> too? Leave the desktop with faster memory (down the road, of
> course) than the "server" chipset?

That shouldn't be too difficult to accept. The server market is
traditionally more conservative about technological changes than the desktop
market is. So it's likely that once DDR2 has proven itself in the Athlon 64,
the Opteron will require a totally new socket other than S940.

Or perhaps Intel's FB-DIMM dreams will come true, and you won't be requiring
a new socket to move to DDR2, because it will work in existing DDR1 slots.

Yousuf Khan

 

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Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

Yousuf Khan wrote:

> K Williams <krw@adelphia.net> wrote:
>> Yousuf Khan wrote:
>>> Probably because a 940 board will truly be able to support 4
>>> DIMMs whereas a 939 board will more than likely be limited to
>>> two DIMMs in reality. When was the last time you saw desktop
>>> boards routinely support more than two DIMMs?
>>
>> Lots of 'em support three. Remember, the 939 is still
>> dual-channel
>> (right?). Are you suggesting that each channel will only have
>> one
>> DIMM? Perhaps that's the only way to make it work, but I'm glad
>> I
>> went with the 940, if so. Still once you've transformed the
>> wires out to the first DIMM, the traces to the second are pretty
>> much parallel, thus I still don't understand the issue.
>
> Well, it's a dual-channel in the sense that the processor reads
> the lower 64-bits from the first DIMM and the upper 64-bits from
> the second DIMM. I don't think it actually puts the two chips in
> separate banks and does bank interleaving in the traditional
> dual-channel sense. This is how Pentium 4's dual-channel works as
> well.

How is this different than interleaving? An address and command is
sent to both channels and each fetch (in the burst) comes from
alternating channels. There are still two independent sets of
wires for the two channels, no? Otherwise I don't see what
dual-channel buys, electrically (note that I haven't looked that
closely).

--
Keith

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

K Williams <krw@adelphia.net> wrote:
>> Well, it's a dual-channel in the sense that the processor reads
>> the lower 64-bits from the first DIMM and the upper 64-bits from
>> the second DIMM. I don't think it actually puts the two chips in
>> separate banks and does bank interleaving in the traditional
>> dual-channel sense. This is how Pentium 4's dual-channel works as
>> well.
>
> How is this different than interleaving? An address and command is
> sent to both channels and each fetch (in the burst) comes from
> alternating channels. There are still two independent sets of
> wires for the two channels, no? Otherwise I don't see what
> dual-channel buys, electrically (note that I haven't looked that
> closely).

Well, I guess it's just that in this case, both DIMMs are really just
extensions of one another inside the same bank. One row-column address is
asserted that activates both DIMMs. Whereas in the bank-interleaved
dual-channel, there has to two separate, but simultaneous, invocations of
rows and columns, one for each bank since they each DIMM resides in separate
banks.

Yousuf Khan