Question about SIMM and parity

So I have this 386DX40 which has 8x30pin memory slots. And I have these memory sticks:

- 8x256Kb (Total 2Mb) Parity unknown (lets call this A)
- 4x1Mb (Total 4Mb) Parity unknown (lets call this B)
- 4x4Mb (Total 16Mb) Parity known: NO PARITY chips (lets call this C).

Any combination of A+B, A+C or B+C does not work, probably due to different timings. However, when put in isolation (and I have to put at least 4 sticks in BANK 0, otherwise the PC does not start):

A - works
B - works
C - boots fine (as in the it passes the BIOS memory test) but immediately after I get "On board parity error at address 0000:0002". This sounds like even the very first stick does not work (yes I moved them around)

There is no option in my BIOS to disable parity check. "C" memory is brand new (yeah I know strange, but I just ordered it off memoryx.com and it has a date of 2014, maybe they still make them?) so I do not think it is damaged. What I think it is, that maybe my motherboard expects parity chips (8+1). Is that possible (as in the motherboard requirement to exist)? The website also sells same version of the sticks I bought for option C but with PARITY enabled. Should I buy those?

Unfortunately I have some kind of clone motherboard, no name, AMI BIOS.

Regards,
Vlad.

That motherboard could be expecting either 9-chip or 4-chip for parity. Besides, if you have ram with no parity, why would you need it on? How many chips are on A, B, C? Maybe a picture of the different breeds you have could help?

I actually found more information. It looks like

A - has parity chip and is parity-on memory - works alone
B - has parity chip and is parity-on memory - works alone
C - non-parity memory - does not work.

That does seem to indicate to me that maybe my motherboard is expecting a parity-on memory stick. Ugh, I wish I would have done that research before buying and posting here

To answer your question

A has 3 chips - works
B has 9 chips - works
C has 8 chips - does not work

Regards,
Vlad.

Back in the days of memory scarcity, there were a couple of manufacturers who cut corners by including a parity encoder on their SIMMs instead of a 9th RAM chip. It cost less, kept most motherboards expecting parity very happy. But of course, any parity checking was a null operation, since every byte that was read back had correct parity.