I'm afraid you are stuck with old PSU's , modern ones are geared towards delivering high amperage on 12 volt rails , old PC's require high amperage on the 5 volt rail. An old PSU should be OK as long as you clean it, change the fan ( usually standard 12 volt 80 mm) and any bad electrolytic caps ( a full recap would be even better ).

Firstly, reliability issues aren't any better or worse on AT and ATX boards from the same era, they basically have the same components, with the last SS7 boards dating to the early capacitor plague era, so check & be prepared to solder.

As for cases - finding an appropriate AT case can be tricky, although I must say I always seem to end up with more than I need - if you keep a lookout for AT systems, you inevitably get some with irreparibly damaged motherboards due to leaked batteries. That gives you a surplus of the cases themselves. But if you don't have the time, space or energy to throw your net out that wide, babyAT boards fit perfectly well into ATX cases (it's almost as if someone designed the ATX standard that way 😉 ), you just need to improvise the single-hole backplate for the keyboard connector.

And then PSUs. On the one hand, I'm a great fan of period parts, and use them where possible. On the other, the issue with light 5V and heavy 12V shouldn't be overstated with SS7 - by modern standards thes CPUs draw very small amounts of power. You can easily get away with a relatively light ATX PSU with an AT-ATX adapter. That said, you can buy modern AT PSUs for reasonable prices from companies like Startech.

raindog1975 wrote:

I'm afraid you are stuck with old PSU's , modern ones are geared towards delivering high amperage on 12 volt rails , old PC's require high amperage on the 5 volt rail. An old PSU should be OK as long as you clean it, change the fan ( usually standard 12 volt 80 mm) and any bad electrolytic caps ( a full recap would be even better ).

I beg your pardon? 😖 For those few watts that a SS7 uses you are good off with any decent modern PSU and a ATX to AT converter.
Perhaps for some very early P4 boards and Athlon boards you need to find a beefy 5V PSU but not for a SS7 build.
Biggest issue will be failing caps on the boards. Some look pristine but are way out of spec by now. I have alot of SS7 (and S7) boards and some are very obvious when they go bad, other not.
And sometimes VRM's will be toast on the board due to age/heat.
Only other issue I could think of is the light corrosion that forms on contact points of RAM and PCI/AGP/ISA slots, more if you live in a high humidity environment. But that is easily solved by cleaning contacts thoroughly before using the board. 😀

Ah, Dionb was a tad faster but same info 🤣

Kahenraz wrote:

There are a lot of AT motherboards for Super Socket 7, many of them with only the AT power connector.

What do I need to consider as potential problems when attempting to build this type of system? I am already aware of the difficulty in sourcing a compatible case and that these boards may not be reliable due to their age. Besides these factors, how should I approach building a system like this? I'm worried most about the power supply as this would be difficult to source and there is no new stock being produced.

You can adapt an ATX 20 pin to an AT power for the board just fine and use just about any ATX power supply. The majority of the power is on 5v, but the the whole system draws maybe 70 watts, and the K6 and pentium pro CPUs are all 35 watts or less. Even less if you are under clocking, which one tends to do with SS7. Any power supply with 20A on the 5v rails is going to do just fine. I have a mini SFX power supply that does that.

Most of the SS7 boards I have seen have both a 20pin and an AT power connector, and you can use either one.

Also, a lot of SS7 boards Iare baby AT/ATX. They have 8 total expansion slots, but two of them are "shared", usually the top ISA and bottom PCI. In an ATX case, this only means you can use either slot but not both.

The only issues I have had with motherboards in this form factor is that they are wider than standard ATX boards, which can make them harder to fit in some cases. The mounting holes though should line up just fine if you move the motherboard stand offs.

Otherwise, finding an AT case can be a bit challenging, especially if you want one in good condition. Most of the ones in decent shape I see on ebay are about 60$-100$, but you pay 40$ or more in shipping. If you have a vintage PC store in your town it would probably be a good idea to check there. I don't see used classic computer show up on places like craigslist or facebook market place very often, but you might get lucky.

Also, you can buy brand new AT power supplies on newegg for about 40$, if you want to go that route. If you have an AT case you are going to need one to mount it properly.