Check the control LEDs. This mainboard has 3 different ones. Flash or light up at the edge of the board when switching on. If everything is OK, they switch off again after booting; if there are problems, they remain lit.

According to the description, this board supports 4800 MHz, 5000 MHz, 5400 MHz, 5800 MHz, 6000 MHz, 6200 MHz, 6400 MHz...

Got this board with Bluetooth You only have to download the drivers via Asus Crate

This is very strange, there may be a defect here. Does the memory work in another system? If it is clear whether the problem is with the RAM or the mainboard, we can of course open a service case: https://helpcenter.galaxus.ch/hc/de/requests/new