Re: my dual channel DDR 400 RAM won't work on any linux distro

Re: my dual channel DDR 400 RAM won't work on any linux distro

[Brien]

Hi again,

(Thanks for replying, John.)

I ran Memtest86, and there're 290 errors that showed up from test 7. But the
thing that I don't understand is, if I use either of the RAM modules alone,
Linux loads and runs perfectly for as long as I've tried; Could it possibly
be a problem with something besides the RAM (e.g. motherboard, CPU)? And I
still don't know if my RAM setup is even supported by Linux -- I'm guessing
that it is though (?).

----- Original Message -----
From: "John Bradford" <john@grabjohn.com>
To: "Brien" <admin@brien.com>
Sent: Wednesday, April 16, 2003 11:11 AM
Subject: Re: my dual channel DDR 400 RAM won't work on any linux distro


> > I have a Gigabyte SINXP1394 motherboard, and 2 Kingston 512 MB DDR 400
(CL
> > 2.5) RAM modules installed. Whenever I try to install any Linux
> > distribution, I always get a black screen after the kernel loads
>
> Can you run Memtest86 on it for an hour or two, and confirm that there
> is nothing wrong with the memory?  Sometimes really obscure faults
> happen to get triggered with Linux, even if the machine appears to
> work with other operating systems.
>
> (By the way, good choice getting a Gigabyte board, I always use them,
> and never have problems with them).
>
> John.
>
>

Re: my dual channel DDR 400 RAM won't work on any linux distro

[Mr. James W. Laferriere]

	Hello Brian ,  Try this then run memtest86 against each mem stick
	seperately .  It sounds as if you tried both at the same time ?
		Hth ,  JimL

On Wed, 16 Apr 2003, Brien wrote:
> Hi again,
> (Thanks for replying, John.)
> I ran Memtest86, and there're 290 errors that showed up from test 7. But the
> thing that I don't understand is, if I use either of the RAM modules alone,
> Linux loads and runs perfectly for as long as I've tried; Could it possibly
> be a problem with something besides the RAM (e.g. motherboard, CPU)? And I
> still don't know if my RAM setup is even supported by Linux -- I'm guessing
> that it is though (?).

> ----- Original Message -----
> From: "John Bradford" <john@grabjohn.com>
> To: "Brien" <admin@brien.com>
> Sent: Wednesday, April 16, 2003 11:11 AM
> Subject: Re: my dual channel DDR 400 RAM won't work on any linux distro
> > > I have a Gigabyte SINXP1394 motherboard, and 2 Kingston 512 MB DDR 400
> (CL
> > > 2.5) RAM modules installed. Whenever I try to install any Linux
> > > distribution, I always get a black screen after the kernel loads
> > Can you run Memtest86 on it for an hour or two, and confirm that there
> > is nothing wrong with the memory?  Sometimes really obscure faults
> > happen to get triggered with Linux, even if the machine appears to
> > work with other operating systems.
> > (By the way, good choice getting a Gigabyte board, I always use them,
> > and never have problems with them).
> > John.
-- 
       +------------------------------------------------------------------+
       | James   W.   Laferriere | System    Techniques | Give me VMS     |
       | Network        Engineer |     P.O. Box 854     |  Give me Linux  |
       | babydr@baby-dragons.com | Coudersport PA 16915 |   only  on  AXP |
       +------------------------------------------------------------------+

Re: my dual channel DDR 400 RAM won't work on any linux distro

[Charles Cazabon]

Brien <admin@brien.com> wrote:
> 
> I ran Memtest86, and there're 290 errors that showed up from test 7. But the
> thing that I don't understand is, if I use either of the RAM modules alone,
> Linux loads and runs perfectly for as long as I've tried; Could it possibly
> be a problem with something besides the RAM (e.g. motherboard, CPU)?

Putting multiple modules in puts a higher load on the address and data lines
supplying the sockets; apparently those two modules are too much of a load for
your motherboard.  You didn't notice a problem in Windows because it doesn't
push the hardware quite as hard.

If your board supports registered (buffered) DIMMs, that would likely solve
your problem.

Charles
-- 
-----------------------------------------------------------------------
Charles Cazabon                            <linux@discworld.dyndns.org>
GPL'ed software available at:     http://www.qcc.ca/~charlesc/software/
-----------------------------------------------------------------------

Re: my dual channel DDR 400 RAM won't work on any linux distro

[Chris Friesen]

Brien wrote:

> I ran Memtest86, and there're 290 errors that showed up from test 7. But the
> thing that I don't understand is, if I use either of the RAM modules alone,
> Linux loads and runs perfectly for as long as I've tried; Could it possibly
> be a problem with something besides the RAM (e.g. motherboard, CPU)? And I
> still don't know if my RAM setup is even supported by Linux -- I'm guessing
> that it is though (?).

Memory support is generally not something handled by the OS.

The more RAM modules you've got, the more reactance on the bus to memory. It may 
be that the second module is loading down the bus enough that the mobo can't 
keep up with the timings.  Try easing off a bit on the memory timings and/or 
strengthening the memory drive strength.

Linux often shows up memory problems when M$ doesn't since it is a) more 
aggressive in its use of memory, and b) capable of driving cpu and chipset 
closer to their theoretical limits.

Chris


-- 
Chris Friesen                    | MailStop: 043/33/F10
Nortel Networks                  | work: (613) 765-0557
3500 Carling Avenue              | fax:  (613) 765-2986
Nepean, ON K2H 8E9 Canada        | email: cfriesen@nortelnetworks.com

Re: my dual channel DDR 400 RAM won't work on any linux distro

[mbs]

On Wednesday 16 April 2003 12:10, Chris Friesen wrote:
>
> Linux often shows up memory problems when M$ doesn't since it is a) more
> aggressive in its use of memory, and b) capable of driving cpu and chipset
> closer to their theoretical limits.
>
<not flamebait, honest question>
you hear this all the time, but do we really have any empirical evidence 
proving this, or is it just what we say to make ourselves feel good when 
Linux won't run on hardware that works fine under other os's?
</not flamebait, honest question>

Re: my dual channel DDR 400 RAM won't work on any linux distro

[Alan Cox]

On Iau, 2003-04-17 at 13:46, mbs wrote:
> <not flamebait, honest question>
> you hear this all the time, but do we really have any empirical evidence 
> proving this, or is it just what we say to make ourselves feel good when 
> Linux won't run on hardware that works fine under other os's?
> </not flamebait, honest question>

Yes, both evidence and in some cases explanation. As to the reasons
quoted in the original message those are probably less true now. Linux
has extremely optimised memory copiers - our AMD memory copiers broke
older VIA chipsets, it took several months until photoshop and other
specialist apps hit the same bug with their mmx/3dnow hand tuned effects
tools on windows and VIA actually fixed it.

Linux also allocates memory in very different patterns to Windows. So
a box that shows the odd crash in windows due to a memory error may show
repeated crashes in Linux an vice versa

Re: my dual channel DDR 400 RAM won't work on any linux distro

[Brien]

The board supports up to 4 GB total (4 DIMM slots), DDR 400/333/266. I'm
normally using 2 * 512 MB DDR 400 on Single 128 bit mode. And the board's
been tested to support up to 4 of the modules that I have (
KVR400X64C25/512 ) shown at :
http://www.giga-byte.com/MotherBoard/Support/TechnologyGuide/TechnologyGuide
_63.htm

motherboard link:
http://www.giga-byte.com/MotherBoard/Products/Products_GA-SINXP1394(GA-8SQ80
0%20Ultra2).htm

I tested both modules seperately just minutes ago, AND GET NO ERRORS on
either one. The errors occur when I have both in.

I've tried running them different speeds (e.g. 333), and it made no
difference in what Linux did (black screened after kernel load).

----- Original Message -----
From: "Alan Cox" <alan@lxorguk.ukuu.org.uk>
To: "Brien" <admin@brien.com>
Cc: "John Bradford" <john@grabjohn.com>
Sent: Wednesday, April 16, 2003 11:15 AM
Subject: Re: my dual channel DDR 400 RAM won't work on any linux distro


> On Mer, 2003-04-16 at 16:41, Brien wrote:
> > I ran Memtest86, and there're 290 errors that showed up from test 7. But
the
> > thing that I don't understand is, if I use either of the RAM modules
alone,
> > Linux loads and runs perfectly for as long as I've tried; Could it
possibly
> > be a problem with something besides the RAM (e.g. motherboard, CPU)? And
I
> > still don't know if my RAM setup is even supported by Linux -- I'm
guessing
> > that it is though (?).
>
> Do your ram modules exceed the number of chips permitted by the board
> vendor ?
>
>
>



----- Original Message -----
From: "Craig Ruff" <cruff@ucar.edu>
To: "Brien" <admin@brien.com>
Sent: Wednesday, April 16, 2003 12:00 PM
Subject: Re: my dual channel DDR 400 RAM won't work on any linux distro


> I've seen similar problems on my Asus A7V board trying to use all three
DIMM
> slots at the top memory speed (PC133).  Any combination of two works fine,
but
> all three results in the system refusing to get past the BIOS power on
> test and configuration.  I don't know if it is just the type of DIMM
> or the size (three 512MB DIMMs maxes out the board).  However, running at
> PC100 speed causes the system to be able to use all three DIMMs.
>
> --
>
> Craig Ruff      NCAR cruff@ucar.edu
> (303) 497-1211  P.O. Box 3000
> Boulder, CO  80307
>
>


----- Original Message -----
From: "Mr. James W. Laferriere" <babydr@baby-dragons.com>
To: "Brien" <admin@brien.com>
Cc: "John Bradford" <john@grabjohn.com>; <linux-kernel@vger.kernel.org>
Sent: Wednesday, April 16, 2003 11:47 AM
Subject: Re: my dual channel DDR 400 RAM won't work on any linux distro


> Hello Brian ,  Try this then run memtest86 against each mem stick
> seperately .  It sounds as if you tried both at the same time ?
> Hth ,  JimL

________________________________

Original Message:

(I posted this on some forums and they recommended that I try here)

Hi,

I have a Gigabyte SINXP1394 motherboard, and 2 Kingston 512 MB DDR 400 (CL
2.5) RAM modules installed. Whenever I try to install any Linux
distribution, I always get a black screen after the kernel loads, when I
have dual channel enabled; If I take out 1 of the RAM modules (either one),
everything works as it should -- it's not a bad module (works perfectly
under Windows by the way). I can't disable dual channel without taking out
half of my RAM, and I really do not want to run with only half of it. Does
anyone have any idea how I can fix this problem, or is it something that
needs to be updated in the kernel?

Thanks for any info.

Re: my dual channel DDR 400 RAM won't work on any linux distro

[John Bradford]

> The board supports up to 4 GB total (4 DIMM slots), DDR 400/333/266. I'm
> normally using 2 * 512 MB DDR 400 on Single 128 bit mode. And the board's
> been tested to support up to 4 of the modules that I have (
> KVR400X64C25/512 ) shown at :
> http://www.giga-byte.com/MotherBoard/Support/TechnologyGuide/TechnologyGuide
> _63.htm
> 
> motherboard link:
> http://www.giga-byte.com/MotherBoard/Products/Products_GA-SINXP1394(GA-8SQ80
> 0%20Ultra2).htm
> 
> I tested both modules seperately just minutes ago, AND GET NO ERRORS on
> either one. The errors occur when I have both in.
> 
> I've tried running them different speeds (e.g. 333), and it made no
> difference in what Linux did (black screened after kernel load).

Do you get errors with Memtest86, with both DIMMs installed, and set
to run at 333?

Also, try checking the power supply volatages are within spec.

John.

Re: my dual channel DDR 400 RAM won't work on any linux distro

[Brien]

I've now tried running the following configurations
-both, with dual channel enabled @ 400
-both, with dual channel disabled @ 400
-both, with dual channel enabled @ 356
-both, with dual channel disabled @ 356
-both, with dual channel enabled @ 333
-both, with dual channel disabled @ 333
-one 400 @ 333 (A), with another module at @ 333 with dual channel disabled
-one 400 @ 333 (A), with another module at @ 333 with dual channel enabled
-one 400 @ 333 (B), with another module at @ 333 with dual channel disabled
-one 400 @ 333 (B), with another module at @ 333 with dual channel enabled
-two complete different modules, both DDR 333 @ 333 with dual channel
enabled
-two complete different modules, both DDR 333 @ 333 with dual channel
disabled
:::all of which are 512 MB each, and that the motherboard was tested to
support:::
and all of them have the same problem: black screen after kernel loads
they all do seem to test with errors when ran with another module, but they
also DO NOT test as errors when they're alone

I'm starting to think it's a problem with my motherboard rather than with
the RAM, because I've tried so many different ways and with different RAM
modules.. but I don't know for sure.. basically every time I try to run any
linux distribution, even if I type (mem=XXXM), it just doesn't work... I can
run some other operating systems without problems, but I know that e.g.
windows is less stressful etc.

hmm

----- Original Message -----
From: "John Bradford" <john@grabjohn.com>
To: "Brien" <admin@brien.com>
Cc: <linux-kernel@vger.kernel.org>
Sent: Wednesday, April 16, 2003 1:01 PM
Subject: Re: my dual channel DDR 400 RAM won't work on any linux distro


> > The board supports up to 4 GB total (4 DIMM slots), DDR 400/333/266. I'm
> > normally using 2 * 512 MB DDR 400 on Single 128 bit mode. And the
board's
> > been tested to support up to 4 of the modules that I have (
> > KVR400X64C25/512 ) shown at :
> >
http://www.giga-byte.com/MotherBoard/Support/TechnologyGuide/TechnologyGuide
> > _63.htm
> >
> > motherboard link:
> >
http://www.giga-byte.com/MotherBoard/Products/Products_GA-SINXP1394(GA-8SQ80
> > 0%20Ultra2).htm
> >
> > I tested both modules seperately just minutes ago, AND GET NO ERRORS on
> > either one. The errors occur when I have both in.
> >
> > I've tried running them different speeds (e.g. 333), and it made no
> > difference in what Linux did (black screened after kernel load).
>
> Do you get errors with Memtest86, with both DIMMs installed, and set
> to run at 333?
>
> Also, try checking the power supply volatages are within spec.
>
> John.
>
>

Re: my dual channel DDR 400 RAM won't work on any linux distro

[John Bradford]

> I've now tried running the following configurations

[snip]

> and all of them have the same problem: black screen after kernel loads
> they all do seem to test with errors when ran with another module, but they
> also DO NOT test as errors when they're alone

OK...  Do you get the same locations failing with one pair of DIMMs as
with another identical pair of DIMMs, or is it just randomly flakey?

> I'm starting to think it's a problem with my motherboard rather than with
> the RAM, because I've tried so many different ways and with different RAM
> modules.. but I don't know for sure..

Are you sure it's not the power supply?  If the voltages are only just
within spec, you could concievably get the behavior you describe.

> basically every time I try to run any linux distribution, even if I
> type (mem=XXXM), it just doesn't work...

I wouldn't even bothing trying to run anything on a machine until it
runs Memtest86 for a couple of hours successfully.

John.

Re: my dual channel DDR 400 RAM won't work on any linux distro

[Brien]

> OK...  Do you get the same locations failing with one pair of DIMMs as
> with another identical pair of DIMMs, or is it just randomly flakey?

never seems to be the same
(maybe a few are, but they've never all been the same--I'd have to look
closely to match any addresses)

> Are you sure it's not the power supply?  If the voltages are only just
> within spec, you could concievably get the behavior you describe.

well, I have a 450 watt power supply that's rated for more than I'm
using--it very rarely even becomes warm after hours of use

the voltages go much higher than they need to; I've also tried adjusting
them and had the same problem

> I wouldn't even bothing trying to run anything on a machine until it
> runs Memtest86 for a couple of hours successfully.

I can with single modules, but not with 2..

I don't know what to do...

thanks for all of the comments/suggestions

----- Original Message -----
From: "John Bradford" <john@grabjohn.com>
To: "Brien" <admin@brien.com>
Cc: "John Bradford" <john@grabjohn.com>; <linux-kernel@vger.kernel.org>
Sent: Wednesday, April 16, 2003 3:28 PM
Subject: Re: my dual channel DDR 400 RAM won't work on any linux distro


> > I've now tried running the following configurations
>
> [snip]
>
> > and all of them have the same problem: black screen after kernel loads
> > they all do seem to test with errors when ran with another module, but
they
> > also DO NOT test as errors when they're alone
>
> OK...  Do you get the same locations failing with one pair of DIMMs as
> with another identical pair of DIMMs, or is it just randomly flakey?
>
> > I'm starting to think it's a problem with my motherboard rather than
with
> > the RAM, because I've tried so many different ways and with different
RAM
> > modules.. but I don't know for sure..
>
> Are you sure it's not the power supply?  If the voltages are only just
> within spec, you could concievably get the behavior you describe.
>
> > basically every time I try to run any linux distribution, even if I
> > type (mem=XXXM), it just doesn't work...
>
> I wouldn't even bothing trying to run anything on a machine until it
> runs Memtest86 for a couple of hours successfully.
>
> John.
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>
>

Re: my dual channel DDR 400 RAM won't work on any linux distro

[John Bradford]

> > OK...  Do you get the same locations failing with one pair of DIMMs as
> > with another identical pair of DIMMs, or is it just randomly flakey?
> 
> never seems to be the same
> (maybe a few are, but they've never all been the same--I'd have to look
> closely to match any addresses)

OK...

> > Are you sure it's not the power supply?  If the voltages are only just
> > within spec, you could concievably get the behavior you describe.
> 
> well, I have a 450 watt power supply that's rated for more than I'm
> using--it very rarely even becomes warm after hours of use
> 
> the voltages go much higher than they need to; I've also tried adjusting
> them and had the same problem

If you've got 10% or more over-voltage, I would be suspicious.

> > I wouldn't even bothing trying to run anything on a machine until it
> > runs Memtest86 for a couple of hours successfully.
> 
> I can with single modules, but not with 2..
> 
> I don't know what to do...

I would contact Gigabyte about it, and mention that your board with
that specific memory configuration fails Memtest86.

It's not a Linux specific problem.

> thanks for all of the comments/suggestions

No problem.  Let us know what happens.

John.

Re: my dual channel DDR 400 RAM won't work on any linux distro

[Walt H]

Do you perhaps have a video card with 128MB on board? I had the same
symptoms as you, and it turned out to be the vesafb driver. It basically
tries to ioremap the entire framebuffer and can't fit it in the reserved
area because it's only 128MB. You can either boot with vga=0 or some
such text mode, which disables the vesafb, or patch vesafb to only
ioremap the space needed for the video mode selected. BTW, the same
applies to rivafb and others I suspect, if your video card has 128MB ram.

-Walt

my dual channel DDR 400 RAM won't work on any linux distro

[Brien]

(I posted this on some forums and they recommended that I try here)

Hi,

I have a Gigabyte SINXP1394 motherboard, and 2 Kingston 512 MB DDR 400 (CL
2.5) RAM modules installed. Whenever I try to install any Linux
distribution, I always get a black screen after the kernel loads, when I
have dual channel enabled; If I take out 1 of the RAM modules (either one),
everything works as it should -- it's not a bad module (works perfectly
under Windows by the way). I can't disable dual channel without taking out
half of my RAM, and I really do not want to run with only half of it. Does
anyone have any idea how I can fix this problem, or is it something that
needs to be updated in the kernel?

Thanks for any info.

Re: my dual channel DDR 400 RAM won't work on any linux distro

[Bruce Harada]

On Wed, 16 Apr 2003 10:59:07 -0400
"Brien" <admin@brien.com> wrote:

> (I posted this on some forums and they recommended that I try here)
> 
> Hi,
> 
> I have a Gigabyte SINXP1394 motherboard, and 2 Kingston 512 MB DDR 400 (CL
> 2.5) RAM modules installed. Whenever I try to install any Linux
> distribution, I always get a black screen after the kernel loads, when I
> have dual channel enabled; If I take out 1 of the RAM modules (either one),
> everything works as it should -- it's not a bad module (works perfectly
> under Windows by the way).

A couple of things to try:
 - Put in both sticks, try booting from a distribution and pass the
   bootloader "mem=960M" as a parameter at the prompt.
 - Just to make sure it's not a memory problem, grab memtest86
   (http://www.memtest86.com/) and try running it for a few hours.
   Unlikely, but you never know.

RE: my dual channel DDR 400 RAM won't work on any linux distro

[Robert White]

I had one-hell of a problem myself relating to memory on my new cutting edge
motherboard.  The problem, it turned out, had everything to do with the
motherboard and the often marginal quality of the ram.  Much investigation
revealed that there were only a few manufacturers of ram that the MoBoard
would "support"

In lay speak, I could put any damn thing I wanted into the first slot, but
anything I did with the second and subsequent slots went all haywire.

The BS layman's speak they gave me at the store was that they had seen a lot
of cases where having "double sided SIMMs" (they were oh-so-usefully
classifying the memory based on whether there were chips on just one side,
or on both sides of the circuit card 8-) in the second and subsequent slots
never worked.

Translating that somewhat vague set of observations by less than top-shelf
observers, and the really scavenging across the manufacturer site where they
listed the specific manufacturer and model numbers of supported SIMs which
were only compatible in specific sets.  (e.g. two of "these" or three of
"those" with no mix-and-match.)  This netted me the following wisdom:

1) Mother Board claims of "up to N gig" are highly contingent.
2) It is nearly impossible to find those contingencies.
3) That is especially true before purchase.
4) The conformant products were all high end components.

This further suggests:

5) Manufacturers are not being completely scrupulous WRT Standards
conformance.
6) Retailers are not well educated about the limits induced by #5.
7) If you want a given amount of memory, make sure you get it all on one
SIMM, on in a matched set, or pre-installed by someone who has the resources
to match a set for you.

8) Individual experience varies *WIDELY* even with the same brand and model
of MoBoard and SIMM.

9) <sarcasm> This is probably a plot to force people to buy the over-priced
1Gig SIMMs instead of a pair of reasonably priced 512K SIMMs </sarcasm>

I don't know the "real cause"(tm) but I suspect it has to do with
tolerances, timing, and evil gremlins that live under SIMMs and exact a toll
on non-union data.  At these speeds 1-half of one percent error can exceed
the noise-floor almost immediately.

Rob.

-----Original Message-----
From: linux-kernel-owner@vger.kernel.org
[mailto:linux-kernel-owner@vger.kernel.org]On Behalf Of Brien
Sent: Wednesday, April 16, 2003 7:59 AM
To: linux-kernel@vger.kernel.org
Subject: my dual channel DDR 400 RAM won't work on any linux distro


(I posted this on some forums and they recommended that I try here)

Hi,

I have a Gigabyte SINXP1394 motherboard, and 2 Kingston 512 MB DDR 400 (CL
2.5) RAM modules installed. Whenever I try to install any Linux
distribution, I always get a black screen after the kernel loads, when I
have dual channel enabled; If I take out 1 of the RAM modules (either one),
everything works as it should -- it's not a bad module (works perfectly
under Windows by the way). I can't disable dual channel without taking out
half of my RAM, and I really do not want to run with only half of it. Does
anyone have any idea how I can fix this problem, or is it something that
needs to be updated in the kernel?

Thanks for any info.


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Re: my dual channel DDR 400 RAM won't work on any linux distro

[Brien]

>but I suspect it has to do with
> tolerances, timing, and evil gremlins that live under SIMMs and exact a
toll
> on non-union data

darn those gremlins! have any repellent?

(sorry if this seems like junk to some people--not going to make it a habit)

----- Original Message -----
From: "Robert White" <rwhite@casabyte.com>
To: "Brien" <admin@brien.com>; <linux-kernel@vger.kernel.org>
Sent: Wednesday, April 16, 2003 4:53 PM
Subject: RE: my dual channel DDR 400 RAM won't work on any linux distro


> I had one-hell of a problem myself relating to memory on my new cutting
edge
> motherboard.  The problem, it turned out, had everything to do with the
> motherboard and the often marginal quality of the ram.  Much investigation
> revealed that there were only a few manufacturers of ram that the MoBoard
> would "support"
>
> In lay speak, I could put any damn thing I wanted into the first slot, but
> anything I did with the second and subsequent slots went all haywire.
>
> The BS layman's speak they gave me at the store was that they had seen a
lot
> of cases where having "double sided SIMMs" (they were oh-so-usefully
> classifying the memory based on whether there were chips on just one side,
> or on both sides of the circuit card 8-) in the second and subsequent
slots
> never worked.
>
> Translating that somewhat vague set of observations by less than top-shelf
> observers, and the really scavenging across the manufacturer site where
they
> listed the specific manufacturer and model numbers of supported SIMs which
> were only compatible in specific sets.  (e.g. two of "these" or three of
> "those" with no mix-and-match.)  This netted me the following wisdom:
>
> 1) Mother Board claims of "up to N gig" are highly contingent.
> 2) It is nearly impossible to find those contingencies.
> 3) That is especially true before purchase.
> 4) The conformant products were all high end components.
>
> This further suggests:
>
> 5) Manufacturers are not being completely scrupulous WRT Standards
> conformance.
> 6) Retailers are not well educated about the limits induced by #5.
> 7) If you want a given amount of memory, make sure you get it all on one
> SIMM, on in a matched set, or pre-installed by someone who has the
resources
> to match a set for you.
>
> 8) Individual experience varies *WIDELY* even with the same brand and
model
> of MoBoard and SIMM.
>
> 9) <sarcasm> This is probably a plot to force people to buy the
over-priced
> 1Gig SIMMs instead of a pair of reasonably priced 512K SIMMs </sarcasm>
>
> I don't know the "real cause"(tm) but I suspect it has to do with
> tolerances, timing, and evil gremlins that live under SIMMs and exact a
toll
> on non-union data.  At these speeds 1-half of one percent error can exceed
> the noise-floor almost immediately.
>
> Rob.
>
> -----Original Message-----
> From: linux-kernel-owner@vger.kernel.org
> [mailto:linux-kernel-owner@vger.kernel.org]On Behalf Of Brien
> Sent: Wednesday, April 16, 2003 7:59 AM
> To: linux-kernel@vger.kernel.org
> Subject: my dual channel DDR 400 RAM won't work on any linux distro
>
>
> (I posted this on some forums and they recommended that I try here)
>
> Hi,
>
> I have a Gigabyte SINXP1394 motherboard, and 2 Kingston 512 MB DDR 400 (CL
> 2.5) RAM modules installed. Whenever I try to install any Linux
> distribution, I always get a black screen after the kernel loads, when I
> have dual channel enabled; If I take out 1 of the RAM modules (either
one),
> everything works as it should -- it's not a bad module (works perfectly
> under Windows by the way). I can't disable dual channel without taking out
> half of my RAM, and I really do not want to run with only half of it. Does
> anyone have any idea how I can fix this problem, or is it something that
> needs to be updated in the kernel?
>
> Thanks for any info.
>
>
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>

Re: my dual channel DDR 400 RAM won't work on any linux distro

[root]

> 
> I had one-hell of a problem myself relating to memory on my new cutting edge
> motherboard.  The problem, it turned out, had everything to do with the
> motherboard and the often marginal quality of the ram.  Much investigation
> revealed that there were only a few manufacturers of ram that the MoBoard
> would "support"
> 
> In lay speak, I could put any damn thing I wanted into the first slot, but
> anything I did with the second and subsequent slots went all haywire.
> 
> The BS layman's speak they gave me at the store was that they had seen a lot
> of cases where having "double sided SIMMs" (they were oh-so-usefully
> classifying the memory based on whether there were chips on just one side,
> or on both sides of the circuit card 8-) in the second and subsequent slots
> never worked.

This has a little basis in fact.

"Double sided SIMMs" can have higher capacitances on the data lines, as there
are more pins connected to the socket.
This means more loading, especially at high speed.

Add in marginal designs, and it can make a difference.

Re: my dual channel DDR 400 RAM won't work on any linux distro

[Mike Dresser]

On Wed, 16 Apr 2003 root@mauve.demon.co.uk wrote:

> This has a little basis in fact.
>
> "Double sided SIMMs" can have higher capacitances on the data lines, as there
> are more pins connected to the socket.
> This means more loading, especially at high speed.
>
> Add in marginal designs, and it can make a difference.

As well, these usually use two banks of memory.

I have a pair of crucial 256 meg sticks in my home pc, one is single sided
and one is double sided.  when I decide that 512 meg isn't enough, I have
to make sure I get a stick that uses only one bank of ram, as my ASUS
p4B533-e shares DIMM2 and DIMM3's banks.  You can only have single sided
dimms in it if you want to use both at once.

Mike

RE: my dual channel DDR 400 RAM won't work on any linux distro

[Peter Svensson]

On Wed, 16 Apr 2003, Robert White wrote:

> The BS layman's speak they gave me at the store was that they had seen a lot
> of cases where having "double sided SIMMs" (they were oh-so-usefully
> classifying the memory based on whether there were chips on just one side,
> or on both sides of the circuit card 8-) in the second and subsequent slots
> never worked.

This is actually a perfectly resonable thing to do. Twice the number of 
chips (and for double-sided modules with stacked chips four times) will 
load the address bus with twice (our four times) the capacitance. Thus the 
siganl flanks will become less and less well defined when adding more 
chips on the bus until some access patterns start to give bad results.

Some motherboards, mostly servers, specify registered memories that have a
buffer circuit to greatly reduce the load on the line drivers. More 
serious technical details from at least some motherboards will specify 
that only a maximum number of chip-loads are possible. Since there are 
only a few address bus driver chipsets the same limitations apply to most 
motherboards. The manefacturer can play some games with voltages and 
buffer strentghs but only so much. At high speeds and several stacked-chip 
modules you really need registered modules.

Peter
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