I have a Gigabyte A520i-ac mini-ITX board that meets your criteria. Hasn't been used in a long time and is untested, but it worked fine last time it was used.
I know this is a long shot, but ... does anyone happen to have a Cisco Meraki MR36 access point mounting kit laying around? I need one for Monday. Thanks!
I have a Seasonic X-Series 850W modular that you can have if you cover shipping. The catch is, you'd need to source modular cables for it.
I should add that one of the screw holes is stripped out.