Windows Memory Diagnostic tool: POS


Y

Yousuf Khan

Not really a problem, just a warning for people. Don't rely on the
Windows Memory Diagnostic tool to debug memory problems -- it doesn't
work. I'm not sure why Microsoft even includes such a useless POS at
all, it's about as useful for memory diagnostics as the BIOS memory
counter, but takes an hour to complete. The BIOS memory counter never
catches anything, but at least it finishes in a few seconds. WMDT is
neither fast nor thorough, i.e. worst of both worlds.

I was diagnosing a problem a friend was having on his machine constantly
hanging. Eventually we decided to run the Windows Memory Diagnostic tool
at the boot menu. It ran two full passes and found nothing wrong
whatsoever. We thought then there was nothing wrong with the memory, but
the problems still persisted. Then I brought my Ubuntu Linux installer
CD's, and ran the memory diagnostics from that one, and within seconds
it found faults in one of the memory modules. Needless to say Windows 7
is running flawlessly now with the faulty module removed. Even if you
never intend to use Linux, keep the Live Installer CD's downloaded just
for the memory diagnostics.

Yousuf Khan
 
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P

Paul

Yousuf said:
Not really a problem, just a warning for people. Don't rely on the
Windows Memory Diagnostic tool to debug memory problems -- it doesn't
work. I'm not sure why Microsoft even includes such a useless POS at
all, it's about as useful for memory diagnostics as the BIOS memory
counter, but takes an hour to complete. The BIOS memory counter never
catches anything, but at least it finishes in a few seconds. WMDT is
neither fast nor thorough, i.e. worst of both worlds.

I was diagnosing a problem a friend was having on his machine constantly
hanging. Eventually we decided to run the Windows Memory Diagnostic tool
at the boot menu. It ran two full passes and found nothing wrong
whatsoever. We thought then there was nothing wrong with the memory, but
the problems still persisted. Then I brought my Ubuntu Linux installer
CD's, and ran the memory diagnostics from that one, and within seconds
it found faults in one of the memory modules. Needless to say Windows 7
is running flawlessly now with the faulty module removed. Even if you
never intend to use Linux, keep the Live Installer CD's downloaded just
for the memory diagnostics.

Yousuf Khan
AFAIK the memory tester available at boot time, is memtest86+.

While using the LiveCD is fine, it's a 700MB download.

If you need to test memory, and are on dialup networking, you
can go to the memtest86+ author's site and get just the memory tester.
There are versions there for floppy, CD, or USB key. When installed
on the floppy, you can't "dir" the floppy, as there is no file system
present. Just a binary that boots immediately.

http://www.memtest.org/

Even memtest86+ isn't perfect, because it can't test the lower
1MB of memory (reserved for 640K region). To test all the memory,
there is a possible solution.

1) Consider installing memory in single channel mode. On a Core i7,
that means you can (and should) test two DIMMs at a time (on a
six DIMM slot Core i7). On an older system with four DIMM slots, you
put two DIMMs on the same channel.

2) Test the memory installed in the single channel as A:B.
Then swap the modules, and test as B:A in single channel.

By doing that, the lower 1MB missed in the first test case (on the
"A" DIMM), gets covered when you swap the modules (then the bottom
of "A" gets tested.

That should cover all of it.

I had a memory problem, where I couldn't start memtest86+. I was
running in dual channel mode (interleaved) and one stick had a dead
chip on it. I could manage to get the memory test program to run,
once I put the DIMMs in single channel mode. I put the bad DIMM into
"high memory", and very politely, memtest86+ started scrolling errors
on the screen at the 512MB mark. Swapping the modules around, resulted
in memtest86+ not being able to start.

The other funny thing was, even though a chip was dead on the DIMM,
the BIOS memory test passed :) Those BIOS guys, are pure comedians.

HTH,
Paul
 
P

philo

Not really a problem, just a warning for people. Don't rely on the
Windows Memory Diagnostic tool to debug memory problems -- it doesn't
work. I'm not sure why Microsoft even includes such a useless POS at
all, it's about as useful for memory diagnostics as the BIOS memory
counter, but takes an hour to complete. The BIOS memory counter never
catches anything, but at least it finishes in a few seconds. WMDT is
neither fast nor thorough, i.e. worst of both worlds.

I was diagnosing a problem a friend was having on his machine constantly
hanging. Eventually we decided to run the Windows Memory Diagnostic tool
at the boot menu. It ran two full passes and found nothing wrong
whatsoever. We thought then there was nothing wrong with the memory, but
the problems still persisted. Then I brought my Ubuntu Linux installer
CD's, and ran the memory diagnostics from that one, and within seconds
it found faults in one of the memory modules. Needless to say Windows 7
is running flawlessly now with the faulty module removed. Even if you
never intend to use Linux, keep the Live Installer CD's downloaded just
for the memory diagnostics.

Yousuf Khan


I've used it and it worked fine for me
but I usually use memtest 86

at any rate, two full passes is not a sufficient test


OTOH: Even using memtest overnight ...on rare occasions it passed RAM
that was still bad.

(When I replaced the RAM the problem went away)
 
Y

Yousuf Khan

I've used it and it worked fine for me
but I usually use memtest 86

at any rate, two full passes is not a sufficient test
It should be more than enough, when Memtest86+ found the problem within
seconds of startup, when it didn't even yet go through one full pass.

Yousuf Khan
 
P

philo

It should be more than enough, when Memtest86+ found the problem within
seconds of startup, when it didn't even yet go through one full pass.

Yousuf Khan

well

that's why I use several utilities
 
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S

Stan Brown

Not really a problem, just a warning for people. Don't rely on the
Windows Memory Diagnostic tool to debug memory problems -- it doesn't
work.
One word: memtest.org

Okay, more words: a free memory tester that really does work. You
need to download the image on a known good computer and burn it to
CD, then boot from the CD.

When I had bad RAM on my personal laptop, it found it. The IT guy at
work now uses it whenever he installs RAM, because it finds problems
right away instead of letting a user run for a while (unknowingly)
with bad RAM.
 
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