For as big as an issue as this was (as I remember it) it doesn't get mentioned much here, so I thought I'd bring it up and see what all of you think.

Prior to ATX, if you built your own computer or bought a "white box" no-name brand or a custom one from a local computer shop, it would be an AT motherboard like the many builds that get posted here.

The advantage of AT is that it was standard; the disadvantage among other things is that only the only opening in the case is the keyboard port, and all the other ports (PS/2 mouse, serial, parallel) had to be on those little ribbon cables, potentially taking away some brackets from the expansion slots if the case didn't have punch-out holes for DB25/DE9. There were exceptions, for example I used to have one of those Biostar 8433UUD boards with the PS/2 mouse port sitting next to the AT keyboard port.

If you instead bought a Packard Bell, Dell, HP, IBM, etc. you didn't get an AT board. Instead you got what is called "LPX", where the ISA/PCI slots are on a proprietary riser card especially for desktop cases, and the on-board ports on the board are a custom-fit for the case the board was designed for. Low-profile PCI cards basically solved the first problem, and ATX I/O shields solved the second one. But essentially, you couldn't grab a "name brand" computer and try to transplant its motherboard into another case like you should be able to today.

Apparently some huge percentage of name-brand manufacturers back then outsourced their motherboard production to Intel, so it's kind of semi-proprietary and semi-standard at the same time.

Here's a writeup about it on Wikipedia: https://en.wikipedia.org/wiki/LPX_(form_factor)

Anyone deal with this trying to fit these boards into a different case? I know someone has posted here doing significant metal cutting/changes to a case but I can't remember which post it was on.

Apparently the "line voltage switch on a rope" power switch that "AT" power supplies had actually came from LPX. It wasn't unusual for an AT case to come with the power supply back then since the power switch wasn't 100% standardized this way.