20.7 does not install on Asrock J3455M. !!!HELP!!!

[bongo]

after doing a test installation on an old x86 itx pc, which only has 1 ethernet interface and no pcie slots, i thought that opnsense looks fiine. so i bought new low power hardware to setup a new router/firewall.

my hardware is an Asrock J3455M board with preinstalled Intel Celeron J3455 cpu, 8gb Kingston Memory (according to Asrock QVL list). Kingston 120gb ssd.
i decided for this mainboard as it provides 3 pcie slots, which allows me to install 3 ethernet cards to serve 3 subnets. (the ethernet cards are not yet installed, it's just mobo/cpu/hd/ram/dvd so far).

the mobo has the latest firmware installed.

after booting from dvd, i start the installer which asks me for kbd layout and font. i accept defaults.
in the installer, i try to select select "guided installation", but nothing happens.
from this point, the system plays a bit dead, i.e. there is no reaction to neither the cursor keys nor the enter key.  (while the mouse pointer can still be moved over  the screen but has no effect).

i tried a ps2 keyboard as well as an usb keyboard, connected to usb2 and usb3 ports, but it's always the same.

in one of my tries, when pressing the cursor up key, i noticed that it scrolled back, showing the transcript of the installation, but there is no way to go on with the installation.

the only command from keyboard that seems to be working is ctrl-alt-del which shuts down the whole thing.

what am i doing wrong? how can i solve?
thanx for your help!

[chemlud]

Playing around with BIOS options appears a good starting point

https://forum.opnsense.org/index.php?topic=6553.0

;-)

[bongo]

after playing around with many bios settings and after at least 50 reboots, i found the solution to complete installation:
it had nothing to do with c-states or cpu clocking. i just had to switch usb support from legacy to uefi only.
but i have no idea how this impacts the ps2 keyboard connected. maybe the ps2 interface of the mainboard is connected over usb in any way...