You probably need a power supply provides -5v. Unfortunately most of the modern PSUs cancel this line.
And you probably need a PSU provides as many Molex D4 connectors as more. Which also hard to find on most of the modern PSU.

My suggestion is to find some 2nd hand -- of course if you could buy a brand new one, that's better --industrial PSUs, such as Advantech's PSU, which is OEMed by FSP.

You will get such as the -5v supply, 6 or more D4 connectors, 6 or more SATA connecters, 2 4-pin power supply for the CPU, sometimes 2 8-pin power supply for the graphic cards, and the decent power supply efficiency.

Well, it depends on your build. Some ISA cards like Sound Blaster 2 need -5 volts. You can use any modern power supply, and for the -5V you'll need a converter like Voltage Blaster.

https://www.philscomputerlab.com/voltage-blaster--5v.html

cloverskull wrote on 2024-12-01, 23:34:

Hey friends, can someone recommend a proper modern PSU that is as close to ideal for a retro build as possible? In this case I'm targeting a S7 rig but in general I'm curious what folks would recommend. I'm a bit PSU ignorant so am not sure how much wattage is required for a retro PC but also how much power on the different voltage rails is needed. Thanks!

Oh boy, that's could be a conundrum depending on your build.
If your sistem doesn't pull much wattage from the 3.3 and 5V line, you coulod get away with a modern PSU (I use one in a Pentium 3 system).
But if you wanna go with a power hungry sistem on those lines (like an Athlon build without CPU power connector), you either find a modern top of the line PSU that can provide at least 25+ amps on those lines (usually those that are rated for more than a 1000W), or you gamble on a used one. And, trust me, it's a gamble to get a 20 years old used PSU.

Focus on getting a PSU that has at least 20A on the +5v rail and if the (Super) Socket 7 motherboard is in AT form factor lacking the ATX power connector, look for an ATX to AT adapter.

I wouldn't worry much about the -5v rail, it is only needed for certain of ISA cards that the OP is unlikely to have.

I've used FSP Dagger Pro PSUs in a Super Socket 7 and a Slot 1 system without issue. I like these PSUs because they're meant for compact builds, so they leave more room in old cases for cable management. Never had a problem with noise or voltages.

They have a couple Molex and a couple SATA connectors - I just adapt the SATA to Molex then connect a Molex splitter to provide as many Molex connectors as needed for the build. This gives me a modern quiet PSU with plenty of legacy connectors.

Regarding -5V, like has already been mentioned, this is usually only needed for some older ISA sound cards. I didn't need it for a regular SB16 (CT2290), AWE32, or AWE64 cards. -5V can also be added any time if you have a free ISA slot using a Voltage Blaster.

Lastly, you didn't ask about Athlon XP but that's one other platform where PSU selection is important - it relied heavily on +5V. With a powerful XP chip and AGP GPU you might want 30+ amps on +5V. For this reason I tend to use period correct PSUs on XP builds since modern builds and PSUs put more power on +12V instead. Anyway, this doesn't apply to Socket 7, just notes for future readers.

Thanks for the feedback, folks! So, hopefully I've been overthinking this and one of my PSUs that are currently unused but semi-new should work. I appreciate everyone's comments.