The power supply of my 386DX computer (an unknown brand M320 motherboard) is not trustworthy anymore, so I'm planning to use an ATX power supply, plus an ATX to AT adapter for P8-P9 connectors.
The thing is that AT power suuplies provide +5V, +12V, -5V and -12V. ATX power supplies, until not much time ago, supplied the same outputs, plus 3.3V, but it seems that the -5V output has phased out, and some ATX supplies mark that pin as NC (not connected).
So when it comes to chosing the right ATX power supply (otoh, one that does not have any fans in the upper side, but in the back side, because ATX supplies are mounted upside down in an AT case and the fan faces the upper side of the case which is most ofently closed) it's hard to tell if the ATX connector includes the white cable that should carry -5V.
So I would like to know if AT-class motherboards need that supply for its internal things (chipset, CPU, SuperIO, etc). I can say that the very usual UM82C206L chip, used to implement most of the AT system chips (DMA, RTC, PIC, Timer, etc) does use only +5V.