They are a bit finicky - you have to sort of angle them in. I know how to do it, but I'm at a bit of a loss as to how to describe it. Hold the connector at an angle where the little nips on the connector fit into the slots, the move it to ninety degrees and press down.

Weird, where did you find a AT PSU with plugs where those six horizontal locking lugs aren't broken off yet? That's really strange.
Well, main hint: Keep the black cables on the inside.
Apart from that, fit the six lugs into the vertical groves of the connector, tilt the plug some 30 degrees towards the keyboard connector, carefully push down.

You can just wiggle them while pressing down and they will eventually get in.

So carefully following all the tips given but to no avail. If I look carefully I really think at least one of those locking lugs are just too long/big. Is it safe to try and make them shorter? Or will the cable get really loose?

Thanks for the help so far though

Edit: It seems to be those 3 longer 'lugs' or whatever they're called that are causing the problem.

Very weird.
It's a normal 386sx board? Maybe post the model or a photo of the whole thing.
And maybe a photo of the connector on the board right from the front and from above, so the area where those lugs are going is visible.

Niborius wrote on 2022-04-29, 20:48:

So carefully following all the tips given but to no avail.

Maybe the problem is the "carefully" part 😆 Don't be afraid to use force in this case he he.

You could also just cut a bit of the plastic pieces yes.

Cuttoon wrote on 2022-04-29, 20:54:

Very weird.
It's a normal 386sx board? Maybe post the model or a photo of the whole thing.
And maybe a photo of the connector on the board right from the front and from above, so the area where those lugs are going is visible.

So this is the model of the motherboard (best page I could find for an exact match): https://stare-pro.translate.goog/catalog/pfco … &_x_tr_pto=wapp

Photo's of the connector:

@Devius: Hehe, I've tried being less careful, but it's not making a difference unfortunately.

Niborius wrote on 2022-04-29, 19:23:

So basically, I have an AT-form factor setup, but I can't for the life of me plug the 12-pin (2x6) connectors to the motherboard […]
Show full quote

So basically, I have an AT-form factor setup, but I can't for the life of me plug the 12-pin (2x6) connectors to the motherboard. It's like the little plastic thingy's on the cable are too long so they're in the way, but I'm not sure.
Below is an image of the connector and the cables. Am I being stupid or is this a known issue?

If I read you correctly....

angle the cable so that the little plastic too long thingys can hook in / under the mainboard connector slots
then with the little plastic too long thingies hooked, angle the cable so that it is in line with the mainboard connector.
then slightly push the cable down onto the mainboard connector. Not yet all the way down.
do the same for both parts of the connector P8/P9
then push both all the way down to the mainboard.

the other options are to either remove the long bits, or remove the plastic bits on the mainboard connector that inhibit the long bits.

It should go like this:

That board is definitely standard, it's a late, budget 386 board.
Connectors look perfectly standard, as well.
http://www.playtool.com/pages/psuconnectors/c … tors.html#oldpc
Just fumble in those lugs laterally, as low as it gets before firmly engaging with the brass pins. Then push the plug down.

Those PSU AT connectors are a bit odd compared to the dozen PSU I have. None have those longer fingers. Some have no fingers, some have just one or two, some have all but the ones that do are all smaller like the Green circled ones.
Use an Xacto knife or similar and trim back the long ones circles in red to match the ones circled in green. It will not hurt and surely should help.

Pretty much as @weedeewee describes it - you need to engage the plastics lugs first at an angle then pivot forward and push down at the same time. Here's how I explained it in a previous post (with pics) - Re: Converting ATX Power Supply to DELL w/ Adapter (Safety Check!)

PC Hoarder Patrol wrote on 2022-04-30, 01:00:

Pretty much as @weedeewee describes it - you need to engage the plastics lugs first at an angle then pivot forward and push down at the same time. Here's how I explained it in a previous post (with pics) - Re: Converting ATX Power Supply to DELL w/ Adapter (Safety Check!)

Note in your picture: Dell 6-Pin 02.JPG
the little fingers are not same as his AT. In your picture they are the tiny ones, in his he has some very large ones.
The largest in your picture is about same as his smaller ones. Is why I suggest trimming them 😁

Shouldn't matter - the Dell pic was only an example of the general technique. I've done it with other AT connectors with lugs as large and it still worked.

PC Hoarder Patrol wrote on 2022-04-30, 01:00:

Pretty much as @weedeewee describes it - you need to engage the plastics lugs first at an angle then pivot forward and push down at the same time. Here's how I explained it in a previous post (with pics) - Re: Converting ATX Power Supply to DELL w/ Adapter (Safety Check!)

Yep, exactly.

Alright, I finally got them in!

You guys were right, I didn't need to cut anything, but it sure as hell wasn't easy. Even once I got the first one in, I was still struggling with the second one 🤣. What mostly helped for me was, like you said, try and get the lugs in first by holding it at an angle, then with a little bit of force and luck they would go in place. I already tried it this way before but only this time they would actually go in.

I'm just glad the 24-pin plugs nowadays are much easier 😜

Thanks everyone!