When turning on it flashes ck cable. and cables are fine

The bios settings maybe set to boot from network or from usb before Ide or sata and if it can not boot from there is reports a boot failure,, usually only stating failure or cable disconnected and goes on the the next boot device,
in windows if you have it set to enable network or log on to network at boot, it will attempt to log on the the network or all networks, if you are not connected to a network through a Ethernet cable it will give you a failure message saying cable damaged or disconnected and look for networks on other devices including wireless