Memory causing problems

[Derk]

Hi,

I have a computer with an ASUS M2A-VM-HDMI motherboard that has an onboard
ATI video chip (X1250) I couldn't install the ATI drivers under Linux.
Therefore I disabled the chip in the bios and built in a Nvidia video card.
I was also unable to activate the nvidia driver without the screen going
black. After spending about 40-50 hours reading everything I could
find  about Nvidia and Ati divers + 3D acceleration, I finally had a bright
idea: I had plugged in 2 extra 1GB memory modules. As soon as I removed
these modules  the nvidia drivers installed without a problem AND the
openSUSE Hibernate Mode worked again.

No my question: It's beyond me why the extra 2 mem modules cause the above
problems. Would 4 identical 1 GB modules (same manufacturer) have worked
without causing this problem? Are the modules defective (didn't get any
error).

Gr, Derk

 

[Paul]

Hi,

I have a computer with an ASUS M2A-VM-HDMI motherboard that has an onboard
ATI video chip (X1250) I couldn't install the ATI drivers under Linux.
Therefore I disabled the chip in the bios and built in a Nvidia video card.
I was also unable to activate the nvidia driver without the screen going
black. After spending about 40-50 hours reading everything I could
find about Nvidia and Ati divers + 3D acceleration, I finally had a bright
idea: I had plugged in 2 extra 1GB memory modules. As soon as I removed
these modules the nvidia drivers installed without a problem AND the
openSUSE Hibernate Mode worked again.

No my question: It's beyond me why the extra 2 mem modules cause the above
problems. Would 4 identical 1 GB modules (same manufacturer) have worked
without causing this problem? Are the modules defective (didn't get any
error).

Gr, Derk

There are a couple possibilities.

The BIOS does initial address map assignments. It allocates space for
PCI cards, PCI Express cards, and the remainder of the address space
is available for memory. Registers, such as "Top Of Memory" in the
Northbridge, are assigned, such that there aren't any overlaps.

Sometimes, the BIOS gets that process wrong. The wrong assignments are
typically noticed when 4GB of memory is present. (Because there might
not be overlap between bus decodes and memory, when a total of 2GB of
memory is present.) On some motherboards, a bogus "USB overcurrent"
error is reported, presumably because a USB resource is overlapping
with some other hardware space.

A second possibility, is the memory remap setting. Two memory maps are
possible, one suited for use with a 64 bit OS, and the other suited to
32 bit OSes. I don't see any remap option in your BIOS, but remapping
would have to be supported, because the manual mentions that 8GB max
of memory is supported. To support that amount of memory, a remap
option would be needed (or perhaps the drivers would need to use bounce
buffers). So while I probably couldn't draw pictures of what the
two memory maps would look like, there is a possibility of a problem
there.

I don't see a BIOS release notes description, that matches your symptoms.
(In other words, no admission of a problem matching your description.)

Another place to look, is vip.asus.com for the Asus hosted forums.
You might take a look here, for symptoms matching your description.

http://vip.asus.com/forum/topic.aspx?board_id=1&model=M2A-VM+HDMI&SLanguage=en-us

When you get a black screen, it is possible an error is logged somewhere,
like a system log or whatever. Reading the error description, might also
hint at the nature of the problem or resource conflict.

I gotta say, the manual and BIOS are a piece of work. Virtually every
feature I looked for in the manual, while reading vip.asus.com threads,
was not documented or present in the BIOS. And that means there are
fewer things a user can adjust to try to fix problems. This seems to
be a trend with ATI chips motherboards - it is almost like ATI writes
the BIOS, because it is consistently crappy. For example, how many
ATI chipset boards, have full memory timing options exposed ?
I remember some of the first ATI chipsets, where the BIOS offered
"fast" and "slow" as the only memory options

Paul

 

[Derk]

First of all, thank you for your very clear answer.

Maybe a dumb question:

I now had the original 2x 1GB in the first 2 sockets and added 2x 1GB in the
other 2 sockets. Would it be possible that it makes a difference when I
swap the DIMMS from socket 3 and 4 to socket 1 and and 2 and vice versa?

Could the problems also be caused by the fact that the 4 DIMM's are from 2
different manufacturers and hence not compatible? If so, I could simply buy
2 extra Kingston 1GB modules. The manual recommends "to buy DIMM's from the
same manufacturer" but elsewhere it only says that pairs of DIMM's should
be from the same vendor.

I agree with you that the BIOS isn't very well documented. I am e.g.still
wondering what the option "Primary Display Adapter" means. ("sets which
controller to use as a primary boot device"). Whatever setting I choose, it
doesn't seem to make any difference.

Thanks again,

Derk

 

[Paul]

First of all, thank you for your very clear answer.

Maybe a dumb question:

I now had the original 2x 1GB in the first 2 sockets and added 2x 1GB in the
other 2 sockets. Would it be possible that it makes a difference when I
swap the DIMMS from socket 3 and 4 to socket 1 and and 2 and vice versa?

Could the problems also be caused by the fact that the 4 DIMM's are from 2
different manufacturers and hence not compatible? If so, I could simply buy
2 extra Kingston 1GB modules. The manual recommends "to buy DIMM's from the
same manufacturer" but elsewhere it only says that pairs of DIMM's should
be from the same vendor.

I agree with you that the BIOS isn't very well documented. I am e.g.still
wondering what the option "Primary Display Adapter" means. ("sets which
controller to use as a primary boot device"). Whatever setting I choose, it
doesn't seem to make any difference.

Thanks again,

Derk

Primary display adapter would be the one used to boot on, would be my guess.

http://www.techarp.com/showFreeBOG.aspx?lang=0&bogno=80

I'm afraid I don't buy this as a "matching module" issue. Maybe you
caused grief for yourself, by not installing the modules in a dual
channel configuration. For example, a matched pair goes in A1 and B1
(same color), where the letters correspond to the channel, and the number
correponds to the DIMM slot position on that channel. On some chipsets,
dual channel requires adherence to using the same slot number on both
channels. On other chipsets, like some recent Intel ones, the only requirement
is that the total quantity of RAM on each channel be the same. Which implies,
you could put Kingston modules in A1 and A2, and OCZ in B1 and B2, and
the recent Intel based motherboard wouldn't mind.

Since the user manual botched the labeling of the DIMM slots, I had to use
this picture to verify the slot labels. The channels are interleaved, with
A1 and B1 adjacent to one another. Which agrees with the color of the
slots, as shown in the picture. The two yellow slots, would be where a
matched pair would go. The table in the downloadable PDF has them
shown in that order as well, but I wanted to check the labels in the
picture of the motherboard, to be sure.

M2A-VM HDMI
http://image.www.rakuten.co.jp/denmapk/img10204407497.jpeg

My guess is, this is related to "4GB total memory". Simply because, there
have been issues before with motherboards not being properly tested with
4GB of RAM present.

If you wanted to test your "4 slot theory", you could purchase 2x512MB of
memory, install 2x1GB plus 2x512MB and see what happens. In that case,
the pairs are dissimilar, all four slots are occupied, but the total ram
is less than 4GB. But to buy the memory to do that, is kinda a waste of
money, unless you plan on leaving the system that way.

There have been some AMD motherboard BIOS, that got confused by the
matching module issue. But I figure by this point in time, the BIOS
writers have figured it out. One manifestation of that problem, was
you'd install four modules, but two would "be invisible". They refused
to be accepted by the BIOS. A later BIOS fixed the issue. Your symptoms
don't sound quite the same as the ones I recollect.

Are all modules double sided ?

Paul

 

[Derk]

Maybe you caused grief for yourself, by not installing the modules in a
dual channel configuration. For example, a matched pair goes in A1 and B1
(same color),

I put matching modules into the same coloured slots, just like the manual
stated.

My guess is, this is related to "4GB total memory". Simply because, there
have been issues before with motherboards not being properly tested with
4GB of RAM present.
If you wanted to test your "4 slot theory", you could purchase 2x512MB of
memory, install 2x1GB plus 2x512MB and see what happens. In that case,
the pairs are dissimilar, all four slots are occupied, but the total ram
is less than 4GB. But to buy the memory to do that, is kinda a waste of
money, unless you plan on leaving the system that way.

How about this: if I plug in 1 of the extra 1GB modules, then I have a total
of 3 GB. Would that give any reliable information or is it a bad idea to
have 1 pair of matching modules and 1 extra module?

Greetings,

Derk

 

[Derk]

Update: I plugged in 1 extra GB module (so 1 matching pair of 2GB total),
making a total of 3GB: the system didn't show any of the errors I
encountered with 4x 1GB. I should maybe plug in the 4th module to see what
happens then.

The 2 original modules (bought the computer as a package, but changed all
hardware but the mainboard by now) only have a sticker syaing:
E38746005870. These modules have chips on both sides.

Derk

 

[Derk]

Update: I plugged in 1 extra GB module (so 1 matching pair of 2GB total),
making a total of 3GB: the system didn't show any of the errors I
encountered with 4x 1GB. I should maybe plug in the 4th module to see what
happens then.

I ran Vista's "Windows Experience Index" and I now saw that using 3GB RAM
caused the 'Memory Score" to drop from 5.6 to 4.8. I guess that that's
caused by not running dual channel mode?

The 2 original modules (bought the computer as a package, but changed all
hardware but the mainboard by now) only have a sticker syaing:
E38746005870. These modules have chips on both sides.

Is there any reason to let the extra 1GB module in the computer now that the
Memory Index shows a drop in performance?

Does the fact that there are no problems when using a 3rd memory module mean
that I probably could plug in 2 extra 2Gb modules?

Derk

 

[Derk]

Maybe you caused grief for yourself, by not installing the modules in a
dual channel configuration.

Interestingly, I found this article (in German) where all sorts of memory
modules were mixed into single/dial channel mode and uneven numbers of
modules. There are lot's of graphics:

http://www.planet3dnow.de/artikel/hardware/speicher/ddr2_performancecheck_am2/14.shtml

According to the test results, all sorts of uneven numbers of modules went
well with the mobo and dual channel versus single channel resulted in
around 10% performance loss.

Gr, Derk

 

[Derk]

I did another test: I plugged the 2 Kingston modules in the first two
(yellow) slots and the other modules in the black slots. So I swapped the
position of the mem modules: same problems with 4x 1 GB.

I took away one of the original modules instead of one of the Kingstons: no
problems with 3x 1GB. I did this to see if one of these new mem modules
caused the problems. answer: no.

So indeed all evidence points at trouble when using 4 GB.

BTW: I identified the original mem module. It had another sicker I couldn't
see at first: TRSDD2001G64U-667CL5F-GX16

Derk

 

[Paul]

I did another test: I plugged the 2 Kingston modules in the first two
(yellow) slots and the other modules in the black slots. So I swapped the
position of the mem modules: same problems with 4x 1 GB.

I took away one of the original modules instead of one of the Kingstons: no
problems with 3x 1GB. I did this to see if one of these new mem modules
caused the problems. answer: no.

So indeed all evidence points at trouble when using 4 GB.

BTW: I identified the original mem module. It had another sicker I couldn't
see at first: TRSDD2001G64U-667CL5F-GX16

Derk

Maybe this is a Linux problem ?

These are the kinds of things I might research.

highmem highmem4g highmem64g pae

http://forum.mandriva.com/viewtopic.php?p=396097

Perhaps the problem is related to how Linux was
setup initially. (I.e. If you'd installed it originally,
with all 4GB present in the machine, the installer may
have used a different kernel choice, or different
boolean values for some of the above flags.

Since I don't have a machine with 4GB here, I've never
dealt with this stuff.

Another option, would be to investigate whether Linux
has an option to limit the amount of physical memory
it uses. Something like "MEM=". Maybe by doing that,
you could dual boot Vista and Linux, while the 4GB
of memory is physically present, and then in Linux,
the Linux system wouldn't attempt to use all 4GB
(or whatever the BIOS offers as accessible memory).

Paul

 

[Derk]

Maybe this is a Linux problem ?

No, I had the same video problem under Vista (which I only use to check
hardware when I have problems).

Perhaps the problem is related to how Linux was
setup initially. (I.e. If you'd installed it originally,
with all 4GB present in the machine

I first installed it with 2 GB and later added 2 GB. I reinstalled
completely with 4GB after I ran into trouble, so I have a 2 and 4 Gb
install.

I'm so curious now, that I'm going to add 2x 2GB modules, just to see if
only the 4GB configuration causes problems.

Thanks again!


Derk

 

[Derk]

SOLVED!!!

I was so curious, I bought 2 extra Kingston 2GB modules. I went home,
plugged them in and ...black screen. I tried all combinations. Even 1
single 2GB modules would cause problems.

Then I was so desperate, I flashed the BIOS, without any real hope it would
solve the problem. I plugged in 2GB, no problems. An extra 2GB, no
problems! 1 more 1GB module. Still OK, 1 more 1GB module. No problem!
So now I'm running 6GB of memory without any problem.

Anyone with an Asus M2A-VM motherboard should flash the bios when having
memory problems. I hope this will help others, since I lost many, many
valuable hours trying to solve this.

I now have a few minor Bios questions, though (forgot to write down a few
settings), thatI'll post in a seperate mail if it's not against forum
rules.

I'm happy!

Thanks again!

Derk