I inquired about the CPU over on ee.se. The chip appears to be an AMD Am386DX-25.
Compare the lower printed number (107M7NX and 107M7NZ), the fonts used, the logo at the bottom-right, and the laser-etched number (23936).
Source: computerbase.de via @SpehroPefhany's answer on ee.se
@njuffa has pointed out that the logo laser-etched ...
Apart from the unrecognized branding on the CPU (ceramic; upper-right in photo) chip, this appears to be a bog standard ISA '386 motherboard, probably running at 25 MHz.
CPU looks like the right packaging for a 80386
Empty 80387 FPU socket
Quadtel "386" BIOS with appropriate late-80s Copyright
50.0MHz oscillator adjacent to CPU; usually provided ...
Going by pinout and socket type it's a pretty generic 80386DX (*1) board based on the VIA FLEX I chipset (SL90xx). Probably 1990/91ish.
It would need a better set of photos - especially of the backside to find some hint. Finding the correct type without further marking is next to impossible, as many did produce following the same layout.
*1 - Visible due ...