If you can't find the drivers, then means it will be the OEM MB version, like HP, dell, etc. Or try Realtek for the network, the chipset driver from AMD
http://support.amd.com/en-us/download/chipset?os=Windows+8.1+-+64 the last one, audio, if you can boot up the PC, then check the PC device manager, and you will know what audio manufacturer is.
Those are the drivers you want.