I have an old home-built machine based on a Q'Lity P3810E-T motherboard
(manufacturer now defunct) and a PIII 600EB slot 1 processor. One of the
two sticks of ram in this machine went bad (reports numerous errors in
memtest86), so I went out to CompUSA to replace it, taking my chances on
the strange brands they carry, not wanting to wait for mail order.

Since what was in the machine before was two 128 mb PC133 dimms, I
bought another 128mb dimm. I noted that the dimm was single sided and
had 8 chips on it, and therefore was using 128 mbit chips. I knew that
256 mbit chips would not work.

However when I plugged in the new dimm the BIOS could only find half of
it, for a total RAM of 192mb. Windows crashes during startup, with
weird display symptoms that make me think that the video memory is being
trashed. Memtest86 can also only find 192mb and reports lots of errors.

I thought I was doing well by getting a stick with 128mbit chips but the
symptoms are just like I have seen before with 256mbit chips on older
machines where only half of the memory is recognized.

When I plug the same dimm into another machine with an Athlon 650
processor and AMD 751 chipset it works just fine.

Do you think it is possible the the manufacturer is actually using
256mbit chips because they are cheaper and is somehow derating it so
that it appears as if it is a 128mb dimm?

The brand name of the dimm is Centon and the chip manufacturer is
Appolo. Yes, that is the correct spelling and no, I can't find any
reference to a chip manufacturer of that name, nor to the ID numbers on
the chips (N003108M16-75, followed by 0310M).

Jeff