Not calling you dumb or anything just normal troubleshooting:
After you installed windows did you install the motherboard drivers for the chipset and network card? Double check in device manager and make sure you don't have any yellow exclamation marks. Windows does not always have generic drivers that work correctly.
Have you tried a different cable? Switch out cables with one of the computers that is working correctly.
Post ipconfig /all listing from all computers to check network settings.