First, as far as I know, SIMMs and DIMMs have never been able
to coexist in any mobo. In addition most older mobos require that
DIMMs be installed with no blank sockets between them.
Additionally many boards required that DIMMs of different sizes
be installed in a particular order, usually the largest DIMM had to be
1st.


"Timothy Lister" <t.lister4XYZ@ntlworldZXY.com> wrote in message
news:rgSSa.6273$47.2028734@newsfep2-win.server.ntli.net...

I thought that was the case as well, yet this configuration resulted in
a total RAM of 48MB, with the new 64MB stick (in the first slot) registering
as 16MB!! Putting the smaller 32MB stick in the first slot & the bigger 64MB
in the second without anything in the SIMM slots (or the remaining DIMM
slot3) is the only configuration that recognises the DIMMs for what they
are!
Previous to this upgrade, I ran 64MB with 32MB DIMM in slot1 & identical
16MB SIMMs in each of the two SIMM slots (I understand that they had to be
installed in identical pairs, according to the manual downloaded from MSI's
homepage)with no problems at all!
I've read through a number of forums & can only find references to
sticks not registering at all due to mobo constraints, etc, but havn't been
able to find reference to problems where DIMMs are only partly registered!
The manual advises against using modules requiring different voltages,
as I believe SIMMs & DIMMs do on my board, but goes on to provide plenty of
info about population rules for mixing the two types! It's a very old board,
lacking any AGP slots, etc!
It's not really a problem for me as I've achieved the upgrade that I
wanted. As I'm learning about the hardware though, I'm just intrigued as to
why my 8x64Mbit module would sometimes only be seen as 16MB!
I'm not looking for any definitive answer as obviously that would
require detailed knowledge of my hardware, etc, rather I was just hoping for
a feasible suggestion as to why this may have occurred! At the end of the
day, I suppose that I'll never know as I'm unlikely to persevere with such
an old board for much longer anyhow! Thanks for the memory pointers, as it
all helps my education in these things!

There are also issues with density of the DIMMs
and their location on the mobo. As I recall, when I
looked at your manual, that there was a chart, a barely
comprehensible one at that, that gave locations for various
combinations of different density memory sticks. That may
be able to explain your location issues. Incidentally your
board is the first I've run across that will accept SIMMs and
DIMMs simultaneously.

"Timothy Lister" <t.lister4XYZ@ntlworldZXY.com> wrote in message
news:WSYSa.2975$D67.290854@newsfep1-win.server.ntli.net...

"Timothy Lister" <t.lister4XYZ@ntlworldZXY.com> wrote in message news:<WSYSa.2975$D67.290854@newsfep1-win.server.ntli.net>...

It's not a good idea to mix +5V SIMM with +3.3V DIMM because the
higher voltages of the SIMM signals will cause the protection in the
DIMM chips to activate, and this gradually wears out the protection
through excessive current and maybe excessive heating. Once the
protection is gone the memory cells are ruined in a hurry. The
exception is with motherboards based on SiS chip sets because they
keep the SIMMs and DIMMs separate, and Gigabyte used to boast of the
ability of their Socket 7 boards to use SIMMs and DIMMs together. If
a motherboard can boot even with only 1 SIMM and no other memory
installed, then it uses one of these SiS chip sets.

Some motherboards allow mixing of the two types of RAM and say so in the
motherboard manual. It is not common to allow this but they exist.

Your problem is that you are using new ram with chips that are of a higher
density. Old motherboards often can't use this ram. Even newer motherboard
can't handle some 256mb stick or 128 because of the denser chips. I have a
new 256 mb that will work only in my newer motherboard, it registers as 128
in the older ones.