¶ PSU
The ALTRAD8UD board doesn't have an 24-pin ATX header but instead comes with a 24-pin to 4-pin adapter so any ATX PSU should work in that regard.
However, it has three EPS 12V CPU headers while most PSUs only come with one or two cables. Each EPS 12V header supports around 300W, so you may connect one or more depending on the power consumption of the board itself and any components attached to it (e.g. CPU - see TDP, DIMMs, PCIe cards, SlimSAS devices etc.)
If you have a modular PSU with more 12V CPU ports on the back but not enough cables, then MODDIY sells then at https://www.moddiy.com/categories/Cables/Power-Supply-Unit-PSU-Power-Cables/Single-Sleeved-Modular-Cables/CPU-EPS-PSU-Modular-Cables/.
You can also buy adapters to convert PCIe cables to EPS 12V cables. For example MODDIY sells them at https://www.moddiy.com/products/Premium-8-Pin-PCIE-to-8-Pin-CPU-EPS-Power-Adapter-Cable-10cm-All-Black.html.
¶ Warning about 4-pin power connector
The diagram in the User Manual is misleading about the orientation of the 4-pin connector.
It suggests that the socket, which is near one of the corners, has a latch facing the DIMM modules. In fact, the latch faces the edge of the board so the clip on the plug should face the closest edge.
¶ Cooler
Since the ALTRAD8UD uses the LGA 4926 socket, options for heatsinks and coolers is very limited.
Alphacool Eisbaer Pro Aurora 240 with the Eisblock XPX Pro LGA 4926 Ampere Mounting Bracket is one option.
Active heatsink coolers from Noctua will also be an option in future (written on 2024-02-22):
NH-U14S AMP-4926: https://noctua.at/en/nh-u14s-amp-4926
NH-D9 AMP-4926 4U: https://noctua.at/en/nh-d9-amp-4926-4u