some sound cards use it, but not that many models I have 2 systems running with no -5 386 and 486 only had a problem with a soundcard before but I have many so used one that works

I'd say no.

It is exposed on ISA slot. So depends on cards you are going to use.

Most cards don't need it. But I have one which does need it - Sound Blaster 2.0 for amp. Newer cards don't need it.

if you really really need it I have seen adapters as part of atx - > at converter that generate -5 but I think its not worth it

Some media Visison cards dont need the -5v?

Thanks for fast replies.
This system definetly will have a soundcard, luckily i have some different brand cards to try (ess, opti, yamaha and als120 chipset).
I will update this topic, and let you know which one will work.

Some motherboards will behave oddly (or will flat out refuse to start) if you omit the negative 5V rail, AFAIK, it is a real crapshoot to know if your mobo is one of these that requires -5V or not.

Most things use the +/-12V rails if they need bipolar supplies. In general, you won't hurt anything by trying. If something doesn't act right (my Media Vision Pro Audio Spectrum 16 card will play audio on high-speed dubbing, for e.g.) then you might need it. My ATX-to-AT adapter doesn't have an inline reg, so I've been thinking of whipping up a quick PCB to take the -12V pin on the ISA slot, run it through a linear reg, and feed -5V back in. In a pinch, I've just crammed some wires into the slot, with a breadboard hanging out on my bench. OK for testing, but it's not terribly secure.

Now i have done some testing - motherboard works just fine, everything works and is stable without -5V.
But i saw some trouble with sound cars, i dont know yet if it is related to this missing -5V rail.

I tried couple cheap Crystal CX4237B chipset based card and ExpertColor Yamaha YMF718-S. Both had soundfx issue in Doom and Wolf3d, lots of loud hissing and cracking involved. Wolfenstein was at some point even playable, but i noticed that opening/closing door soundfx triggered almost always this awful noise problem.

Older games, that i tried, worked just fine.

Will do some more testing with differend soundcards and PSU with -5V rail.

So, tested my system with regular AT PSU, everything worked like charm. Seems, that these soundcards use -5V only when stereo sound (sb pro or SB16) is used. Older games with adlib and soundblaster (mono) support sound fine.
My last hope is opti chipset based soundcard, that i recive next week. If that doesnt work, i need some kind of voltage inverter that converts +5V to -5V. Ideas anyone, how to achieve that?

It's not common but I've come across motherboards without ISA slots that have older (than the mobo) ISA based onboard sound chips that need the -5v to work.
They were either MSI or BioStar boards. Others may have done that too.
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