Most AT power supplies are 150 - 230watts but the system board itself wont use any where near that, what's important is -5v which you wont get with a modern PSU unless you use something like a Voltage Blaster to add the -5v to the ISA bus.
You can find Voltage Blasters on eBay for pretty cheap so it wont be much of an issue but most 486 era sound cards wanted -5v to work, the other thing to be aware of is the +5v Amps, I doubt a modern PSU is going to have issues here with a 486/Pentium class machine but its something to be aware of that you want as many AMPs on the +5v rail as you can find.

TrashPanda wrote on 2022-08-14, 13:20:

[...] what's important is -5v [...]

It's really not (unless you want to use one of the very few cards that need it - such as a SB 2.0). 😀

TrashPanda wrote on 2022-08-14, 13:20:

[...]but most 486 era sound cards wanted -5v to work[...]

Most? The only one I know of is SB 2.0. Earlier (SB 1.5) and subsequent sound blasters work just fine without it.
In fact, it's very easy to tell if you need it. Check the card's pins. If the -5V pin (on the back of the card --> 5th pin from the left) has a trace that leads somewhere, then -5V is needed, otherwise no.

last 486 I tested was about 4-5 amps on 5V with a CF card
-5V really isn't required by that many cards, certainly not "most" ^^

bloodem wrote on 2022-08-14, 13:38:

TrashPanda wrote on 2022-08-14, 13:20:

[...] what's important is -5v [...]

It's really not (unless you want to use one of the very few cards that need it - such as a SB 2.0). 😀

Well I guess you could use a different sound card that doesnt need it.

TrashPanda wrote on 2022-08-14, 13:40:

Well I guess you could use a different sound card that doesnt need it.

You'd definitely want to use a card that doesn't need it, because SB 2.0 (the only card I've ever tested that actually needs -5V) is not really suitable for a 486 (or even a 386).
A 486 works very well with a SB Pro 2 or even a SB16 (or other equivalent cards), and those don't need -5V at all.

Regarding power, all modern power supplies that I've tested worked just fine with a 486. Total power consumption (at the wall) is ~ 30W or less.
In fact, all (good quality) modern power supplies work fine with most old hardware except for fast Athlon/Athlon XP builds - those that don't have the CPU ("P4") connector.

bloodem wrote on 2022-08-14, 13:47:

You'd definitely want to use a card that doesn't need it, because SB 2.0 (the only card I've ever tested that actually needs -5V […]
Show full quote

TrashPanda wrote on 2022-08-14, 13:40:

Well I guess you could use a different sound card that doesnt need it.

You'd definitely want to use a card that doesn't need it, because SB 2.0 (the only card I've ever tested that actually needs -5V) is not really suitable for a 486 (or even a 386).
A 486 works very well with a SB Pro 2 or even a SB16 (or other equivalent cards), and those don't need -5V at all.

Regarding power, all modern power supplies that I've tested worked just fine with a 486. Total power consumption (at the wall) is ~ 30W or less.

I was thinking more along the lines that if you are building a 486 then its possible OP has ideas to play around with hardware from that era, I know if I had a nice 486 Id definitely want to check out the likes of Adlib and such which does want -5v, so yes its not a "need" but rather nice to have, its why I suggested a Voltage Blaster since there is no other easy way of getting it from a modern PSU.

TrashPanda wrote on 2022-08-14, 13:55:

I was thinking more along the lines that if you are building a 486 then its possible OP has ideas to play around with hardware from that era, I know if I had a nice 486 Id definitely want to check out the likes of Adlib and such which does want -5v, so yes its not a "need" but rather nice to have, its why I suggested a Voltage Blaster since there is no other easy way of getting it from a modern PSU.

The Adlib does not need -5V. It's missing the -5V pin completely. 😀
The voltage blaster is great (I've also built a few myself), but I only use it with SB 2.0, since, out of all my 300+ sound cards, this is the only one that needs -5V. 😁

PS: the Adlib Gold doesn't need -5V either (not that we'd care, since most of us will never have that card 😁 ).

Just in case anyone has doubts, this is the back of the Adlib card, and the missing pin (circled in red) would've been the -5V pin.
Some cards do have the pin (but without having any trace). Obviously, those don't need -5V either.

bloodem wrote on 2022-08-14, 13:58:

The Adlib does not need -5V. It's missing the -5V pin completely. :-) The voltage blaster is great (I've also built a few myself […]
Show full quote

TrashPanda wrote on 2022-08-14, 13:55:

I was thinking more along the lines that if you are building a 486 then its possible OP has ideas to play around with hardware from that era, I know if I had a nice 486 Id definitely want to check out the likes of Adlib and such which does want -5v, so yes its not a "need" but rather nice to have, its why I suggested a Voltage Blaster since there is no other easy way of getting it from a modern PSU.

The Adlib does not need -5V. It's missing the -5V pin completely. 😀
The voltage blaster is great (I've also built a few myself), but I only use it with SB 2.0, since, out of all my 300+ sound cards, this is the only one that needs -5V. 😁

PS: the Adlib Gold doesn't need -5V either (not that we'd care, since most of us will never have that card 😁 ).

Just in case anyone has doubts, this is the back of the Adlib card, and the missing pin (circled in red) would've been the -5V pin.
Some cards do have the pin (but without having any trace). Obviously, those don't need -5V either.

Hmm the few models I've seen do have that pin, not that I ever had the presence of mind to check the traces for it.

Mind you Adlib is pretty rare around my parts so I haven't seen a lot of models in the flesh.

The question then is ..why was the -5v line enough of an issue to bother designing a Voltage Blaster, surely it was not because of that one sound card.

Most Media Vision PAS, PAS16, etc need -5v, for the audio amps iirc

Horun wrote on 2022-08-14, 14:22:

Most Media Vision PAS, PAS16, etc need -5v, for the audio amps iirc

Yes, the PAS cards I've seen do need -5V (don't own any, though).
But then again, those aren't really cards that non-collectors would want in their retro PCs.