As far as power requirements go, 350W should be plenty for a 486 system imho.

GabrielKnight123 wrote on 2023-01-17, 09:48:

My corsair RM550X died and I have to replace it for my 486, it's being used with an adapter that has a 5 watt resistor on (from memory) the 3.3 volts but I'm not sure if all the new ATX power supplies are good for a 486 when it comes to watts on each rail for example would the Cooler Master MWE GOLD 550 V2 be good I've heard not to throw a high 800 watt psu at a 486 hence the lowish cooler master 550

Hello,

I don't fully understand what you mean.
A typical AT power supply for a 486 has the following specs:
+5V 20A
-5V 0.5A
+12V 8A
-12V 0.5V.

As far as I know -5V are used only by some very old cards, so you have to compare only the other 3. I believe 0.3Amps on the -12V should be fine, too.
Most important for a 486 is the +5volts line, 3.3V is not needed at all.

CoffeeOne wrote on 2023-01-17, 10:42:

Hello, […]
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GabrielKnight123 wrote on 2023-01-17, 09:48:

My corsair RM550X died and I have to replace it for my 486, it's being used with an adapter that has a 5 watt resistor on (from memory) the 3.3 volts but I'm not sure if all the new ATX power supplies are good for a 486 when it comes to watts on each rail for example would the Cooler Master MWE GOLD 550 V2 be good I've heard not to throw a high 800 watt psu at a 486 hence the lowish cooler master 550

Hello,

I don't fully understand what you mean.
A typical AT power supply for a 486 has the following specs:
+5V 20A
-5V 0.5A
+12V 8A
-12V 0.5V.

As far as I know -5V are used only by some very old cards, so you have to compare only the other 3. I believe 0.3Amps on the -12V should be fine, too.
Most important for a 486 is the +5volts line, 3.3V is not needed at all.

I quickly looked for the cheapest available power supply in Austria and found this:
https://mylemon.at/artikel/akyga/ak_b1_400/ak … tzteil-400.html

So it is fully in spec for a 486 (when -5v is not needed). I am not sure about the quality of this (no-name?) brand, this should be just an example.

Basically every atx PSU will do. There are not many 486s that burn away more than 80W. That's the 12v line included. So everything above 200W should have a 15+ amps on the+5v line and that's fine. Just make sure you've got a good PSU: some crappy stuff will not regulate the +5v line very well without a serious +12v load.

Avoid the noname ones as they tend to have deceptive specs and lower reliability even if it won't use much power.

I agree quality is a big factor for steady voltage when your 486 has a MPU-IPC-T card and a pro audio spectrum 16 the only gripe I have with all ATX psu's of today is the psu fan is on the top, there is not much room between the top of the psu and the inside top of my AT case for air flow if I could turn the psu upside down it would be much better

Coffeeone the amps from an old psu on all rails should be exceeded by a new psu I am not sure if new psu's have the same or better watts per rail for example the +5 on the cooler Master has a shared +5 and +3.3 of 100 watts and the -12 of 3.6 watts, sorry I don't know much about watts or mathematical formula's to get watts from amps

GabrielKnight123 wrote on 2023-01-18, 01:39:

I agree quality is a big factor for steady voltage when your 486 has a MPU-IPC-T card and a pro audio spectrum 16 the only gripe I have with all ATX psu's of today is the psu fan is on the top, there is not much room between the top of the psu and the inside top of my AT case for air flow if I could turn the psu upside down it would be much better

Wait what? What you wrote struck me as odd so I went and checked. I mounting holes for PSUs haven't changed in like 40 years as far as I can tell. I can mount a regular ATX power supply inside any of my AT cases the same way I would in an ATX case. The fan is facing down towards the motherboard, as it should.