DON'T DO THAT! IT WILL TOAST YOUR BOARD AND/OR PSU!

What you have is an early ATX PSU with AUX 3.3V connector. What you need is an AT PSU with P8 and P9 connectors, which are physically the same as the AUX 3.3V connector, but wired very differently. This connector will short all kinds of things in this way.

Failing an actual AT PSU, you need an adapter cable from ATX to AT, and then connect the two AT P8 and P9 connectors so that the black (ground) wires are in the middle.

dionb wrote on 2021-03-16, 17:26:

DON'T DO THAT! IT WILL TOAST YOUR BOARD AND/OR PSU!

What you have is an early ATX PSU with AUX 3.3V connector. What you need is an AT PSU with P8 and P9 connectors, which are physically the same as the AUX 3.3V connector, but wired very differently. This connector will short all kinds of things in this way.

Failing an actual AT PSU, you need an adapter cable from ATX to AT, and then connect the two AT P8 and P9 connectors so that the black (ground) wires are in the middle.

appreciate the advice. i havnt powered it up although i was tempted! so im glad i didnt!!

do you remember its original usage being on an atx psu?

i ordered said AT adapter yesterday so hopefully it will be here tomorrow.

i have read that AT adapter may cause issues with ISA sound cards, i have an Awe32, do you happen to know if this will cause sound issues?

You can buy an ATX to AT adapter like this one, and basically use any modern PSU.
ISA sound cards don't have issues with AT adapters, some (not many) ISA sound cards (such as the Sound Blaster 2.0), do have issues with modern PSUs, since these don't supply -5V (but there are workarounds for this as well).
However, your AWE32 does not use -5V, so you're fine.

Scott8bit wrote on 2021-03-16, 17:54:

do you remember its original usage being on an atx psu?

That connector was part of the ATX spec for a while during the early 2000's, it was intended to provided additional +5V and +3.3V lines to the motherboards (that's why there are red and orange wires). I've seen it mostly on early P4 motherboards, but I think it was also used on some P3 and Athlon boards.

Also, to add even more confusion: there is another earlier connector of the same type which was used to "extend" AT power supplies by adding a 3.3V line, sort of like a "proto-ATX". But that one is slightly different from yours, as it had only +3.3V (no red +5V wire) and it's not part of the ATX standard, it was included on some OEM AT units to provide 3.3V to early PCI motherboards.

Here's some good info on these cables:
The Auxiliary connector has three ground wires (black), one 5V wire (red), and two 3.3V wires (orange).
http://www.playtool.com/pages/psuconnectors/c … ectors.html#aux

The old AT cables had zero 3.3V wires. On the particular side of the AT connector you're dealing with, the old connector had a mixture of ground pins, two 5V pins, and the -5V (white).
http://www.playtool.com/pages/psuconnectors/c … tors.html#oldpc

The mismatch in your photo would be on Pins # 3, 4, and 5. I don't know what exactly would happen if you powered on (definitely your system wouldn't work, but I don't know what might get destroyed)... but it's a good thing you didn't!

TheMobRules wrote on 2021-03-16, 18:39:

Also, to add even more confusion: there is another earlier connector of the same type which was used to "extend" AT power supplies by adding a 3.3V line, sort of like a "proto-ATX". But that one is slightly different from yours, as it had only +3.3V (no red +5V wire) and it's not part of the ATX standard, it was included on some OEM AT units to provide 3.3V to early PCI motherboards.

Can I add more confusion? 😁
About one year ago at the fleamarket I stumbled upon a fairly high-powered (300W I think) NOS AT power supply. Snatched it, of course. It has a third connector besides P8 and P9, but to my surprise it provides +5V instead of +3.3V!