[KLUG Members] PC133 memory in PC100

[Adam Tauno Williams]

> > Last I checked, PC100 and PC133 DIMMS can be installed however.  SIMM
> > (Single inline memory module) needs to be in pairs, and those are
> > usually 72 pin.  DIMMs (Dual inline memory module) can be in one at a
> > time. I have 4 completely different sizes, and two speeds of ram in my
> > current workstation (dual 550) and it doesn't complain a bit.

This all depends on the motherboard/chipset really.  I have machines
that take DIMMs singly (most in fact) and some that require them in
pairs.  I have machines that take PC100 and work fine with PC133 memory,
and some that don't (Compaq iPAQs seem really grumpy about mixed pairs).
Sometimes a pair of PC133 in a PC100 machine works while a PC100/PC133
pair doesn't.  I spent enough time as an electrical technician to not be
terribly surprised by this - it is very easy to influence the timing of
a digital circuit - and small variations in clock can result in some
very strange behavour.  Get some old 7400 logic chips and a breadboard
and you'll discover this even at a few hundred hertz; and new "ludicrous
speed" memory buses...

> > Try just the PC100, and boot.  Get memtest86 (www.memtest86.com) and
> > test each module individually.
> Got it, tested as pair, locked up.  I'll try testing just the pc133
> tonight.

This is exactly what we see with our Compaq machines.  Windows will not
even get through a boot process, and memtest freaks almost immediately
until it freezes.  Sometimes rearranging gives you longer until total
crash, but it doesn't fix the problem.

> > Also, PC100 and PC133 can still be found at your local best buys.  I was
> > price shopping a few weeks ago.
> Looked at BB, but only found PC133.

http://www.memoryplace.com

We've even purchased memory, not used it, and they let us send it back
six months later.
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