I'm pretty sure most or all IBM boards and a lot of name-brand OEM systems forced parity checking while some XT clone boards and a lot of older 286 boards have the option selectable by switches or jumpers and late gen 286 boards usually offer it in the BIOS. Then there's a handful of 8088 and 286 boards that lack parity support entirely and have DIP RAM sockets only 8 or 16-bits wide. (or in at least one case with a Hedaka Turbo XT board using a Citygate chipset, with only 4 bits wide and latched to 8-bits for the CPU)

But for late generation 286 boards and 386 boards, well into the Intel 486 era and probably into the AMD and Cyrix 486 period in the early 90s, there seems like there's at least some motherboard or BIOS revisions that omit the parity selection option and thus usually force it to enabled.

And while it wasn't the most common thing to have 8-bit wide 30-pin SIMMs, they were certainly out there along with a number of 9-bit SIMMs with non-matching parity chips, usually with parity chips being slower. (while I have 1 70 ns SIMM with a 60 ns parity chip, I've got several 60 ns 4MB SIMMs with 70 ns parity chips, and while I didn't look up the particular datasheets to compare exact timing specs, that normally leaves memory timing limits slower with parity enabled)

One of the AMI BIOS revisions of the Biostar MB1212C using the CHIPS SCAT chipset has an option for parity, and an older revision BIOS that lacks this feature. (though the older BIOS also offers more access to chipset registers and manual tweaks ... but not the parity selection)

And I've got one 1991 or 1992 Biostar MB3486 (UMC chipset 386/486 board) that also appears to lack any parity selection option along with options for enabling/disabling memory test above 1MB or the memory test beep sound.

I also considered the possibility for the BIOS auto-detecting the presence of parity RAM, but installing non-parity SIMMs just led to the system hanging at the memory test. (presumably with the 64k base RAM failure beep code, but I didn't have a speaker connected at the time)