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Jorden
9th August 2000, 14:51
This might help some people out there with memory problems.
<hr>
Newsgroups: microsoft.public.win98.gen_discussion
References:

Hi, Ant. There are several possibilities for your problem:

1. Re-enable the L2 cache and *enable* the L2 cache ECC.

The above will allow you to check whether the L2 cache
inside the CPU is defective or not. If you get blue-screen
errors telling you the ECC has detected memory errors
in the L2 cache memory -- then the L2 cache is at least
intermittent and the CPU should be replaced.

Note: This is a very-low-probability item. L2 cache in
Coppermine (Pentium III) chips is *very* thoroughly
tested by Intel before the chip leaves the fab.

2. If enabling the L2 cache ECC solves the problem and
the memory errors do not return, then the ECC is changing
the cache-timing in such a manner as to allow the two
memory modules to work together properly. This is not
unusual, but you may wish to update the flashBIOS to
see if you can get reliable operation with ECC disabled.
(See Item 6 for more details.)

3. If enabling the L2 cache ECC changes nothing, then the
ECC is irrelevant to your problem and you need to look
elsewhere.

4. It is *very* common for memory-module-mismatch to cause
problems with writeback from the L2 cache memory to
main memory. The usual cause for this problem is different
timing in the two memory modules that is too subtle for
the BIOS to detect and compensate for automatically.

Consequently, the next thing to do is confirm that both
memory modules work properly independently.

You know your old module is reliable -- because it worked
properly for months before you got your new one.

So, take out the old module and install the new module in
the slot where the old module was located. Do *not* just
take out the old module. Move the new module where
the old module was located.

Run for a few days with just the new module in place. If
things screw up with only the new module in place -- it is
defective and should be returned for replacement.

5. If both modules work properly independently, then the
next thing to do is check whether swapping the location
of the two modules will solve the problem.

With all motherboards that autodetect memory-timing,
the slowest module must *always* be installed in the first
memory slot -- as this is the slot which is probed by the BIOS
at startup to determine the global memory-timing parameters
for the entire memory pool.

All memory-access must be done no faster than the
slowest-reacting SIMM/DIMM in the pool. Since you know
that having the old module in the first slot doesn't work, try
running with the new module in the first slot and the old
module in the second slot. If this works, you've solved your
problem.

6. If you still have problems no matter whether the old module
is in the first or second slot -- but either module works properly
alone -- then you have a memory compatibility problem.

First step to fixing this is to upgrade to the latest motherboard
flashBIOS available for your machine. Many motherboard
manufacturers change BIOS parameters to improve memory
module compatibility as the manufacturer learns more about
how the BIOS and that particular motherboard interact.

7. If updating the BIOS does not fix the problem, then try a
matched set of memory where both modules are from the
same manufacturing batch.

If the above does not solve the problem, then check out
a matched set of very-high-quality memory from a
manufacturer such as Micron (Crucial Technology) or
Samsung (Corsair).

If the above does not solve the problem, then it is possible
you have an intermittently-defective chip on the motherboard
itself -- where the part of the chip which is not working
correctly is only accessed once you install the second
memory module. In that case, the only fix for your problem
is a new motherboard.
<hr>

Jord.