Using DIMMs of Different Speeds

[Mike Bilow]

It was a myth then and it is a myth now.  Memory runs at the speed of the
machine, not at the speed of the memory.  If all of the memory is rated
for at least the speed required by the machine, then it will all work in
sync at whatever speed the machine operates.

That said, it is a bad idea to mix different TYPES of memory where that
might be possible for some machines.  For example, in the old days of
30-pin SIMM, it was a bad idea to mix 3-chip and 9-chip memory, but this
was because their timing requirements were different.  In more modern
72-pin SIMM, it is a bad idea to mix EDO and non-EDO (FPM) memory,
although it is possible to run EDO memory at the slower speed of FPM.  
With 168-pin DIMM, there are actually incompatible types which simply will
not work at all if mixed, such as EDO and SDRAM, and you must get whatever
is compatible with the machine.

-- Mike


On 2000-05-06 at 20:55 -0400, Chuck Noyes wrote:

> Years ago, I know that using memories of different speeds was a bad idea,
> but what now?  Is the firmware in PCs these days smart enough to deal with
> memories of different speeds?


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