Keyboard is not handled in appropriate way.
Mainboard has a combo PS/2 port. Regular Compaq keyboard was not recognized by this.
Mainboard did not recognize the mentioned keyboard, nor after attaching a PS/2 to USB adapter and connecting it to USB port ; so BIOS was not accesible.
Asked from a friend a genuine USB keyboard, made some BIOS settings (boot sequence, memory frequency) and was able to install Win7 from CD-drive.
Now, the POST halts -- during POST it seems that the keyboard is obstructing the process.
It seems that will never allow me to enter BIOS, as keyboard is not recognized by BIOS.
I tried several USB ports (backside, directly connected to MB) or from PC-front.
If the keyboard is removed from USB during start-up, the BIOS makes progress trough POST and eventually, after booting and loading Windows till a certain phase, keyboard becomes again functional.
I checked : the mainboard came with latest BIOS available.
Re set cmos to clear bios to factory. Then enter bios and look for usb power up , turn to on. Look thru bios usb options for kboard support, obviously you want it to look for usb in front of ps/2 board for further bios adaption.
Check manual for settings , but try not to cry at the translations, it can be tedious to work out whats what.
I have seen this.
In the bios there will be an option for legacy usb devices, it must be set to enabled in the bios menu. The problem should then be resolved with your keyboard.
Part of problems was solved using hints from your response.
After entering BIOS : "Advanced" ; step to " Advanced PCIPnP"
"Plug And Play O/S" set "Yes"
in "USB Configuration" set "Legacy USB Support" from "Auto" to "Enabled"
BIOS did not easily set back to initial values : clearing memory only with the jumper was not enough : only after removing battery for some minutes went back to a state were it received input from keyboard.
Now a USB keyboard works both in BIOS, enabling further settings // after boot work with the OS
Still my PS/2 keyboard is not recognised : no LED is up on the keyboard -- seems like getting not 'power'
Any hope for solving ?
I am quite sad because of this.