I use an adaptor. Here's one I just spotted on ebay -

http://cgi.ebay.co.uk/ATX-to-AT-Motherboard-P … id=p3286.c0.m14

Regarding the -5v issue, I think you only need it if a specific card (eg sound) requires it. To the best of my knowledge, I think it's fairly rare that you need this. I think the LAPC-i needs it, and a really old 8-bit SoundBlaster card, but I'm sure other people will be able to respond to that question better than I can.

What I can be sure about though, is the AT to ATX PSU adaptor works very well.

Power OK (ATX) is the same as Power Good (AT)

Power OK (ATX) is the same as Power Good (AT)

Thanks.

Here's one I just spotted on ebay.

At $34.50 shipping to the UK 😳 ? Sorry, this project is on a shoestring budget! 🤣

Don't AT PSUs usually get controlled by a power switch (always on or always off) on the case, while ATX's get controlled by a power button (only on while pressed)? Do AT-to-ATX adapters somehow account for that?

HunterZ wrote:

Don't AT PSUs usually get controlled by a power switch (always on or always off) on the case, while ATX's get controlled by a power button (only on while pressed)? Do AT-to-ATX adapters somehow account for that?

Please check out the photo on the above ebay auction link - it shows the adaptor alongside a nice chunky On/Off power switch. 😀

HunterZ wrote:

Don't AT PSUs usually get controlled by a power switch (always on or always off) on the case, while ATX's get controlled by a power button (only on while pressed)?
Do AT-to-ATX adapters somehow account for that?

The adapter doesn't have to care about that.
When you leave the mainboard out of the loop, an ATX PSU has to be turned on/off by a switch: As long as the green "Power On" wire is connected to ground, the ATX PSU will run, otherwise it will go to standby mode.
ATX boards have a circuit that "emulates" the switch for the PSU because they need to be able to control the PSU for power management (i.e. wake up/shut down automatically).

5u3 wrote:

ATX boards have a circuit that "emulates" the switch for the PSU because they need to be able to control the PSU for power management (i.e. wake up/shut down automatically).

Ah, that makes sense.

I know about shorting the green wire to ground to force the PSU to turn on, as my former roommate and I did that about 5 years ago with an old spare ATX PSU so we could use it to power up components (fans, LEDs, drives, etc.) on a workbench without having to plug them into a computer first.

Yeah, I've just tied the green to a black wire, and use the PSU switch on the back to turn it on/off for the time being. Seems to work, I get a light on my etherlink iii, but all else seems dead so far - ie. no video.

Do you have a multimeter to test the voltages at the AT connector? Those connector blocks can be tricky sometimes...

Good point, I've now checked the voltages both at the block and to be completely sure, at the AT connector. All OK give or take 5%.

Now noticed that the board jumpers are not set for a DX4 cpu - it came with an AMD DX4-100 fitted and I kind of assumed that the jumpers would set right as it was described as working 😒. So I better find out the jumper settings I need - for all I know none will be right; hopefully nothing will have been broken in the meantime.

As it turned out, the jumpers were ok and it now boots 😀 .