Find a connector on the motherboard labeled HD TMP or HDD TEMP.

If you have trouble locating it, trace the two-wire temperature cable you disconnected from the old hard drive.

If the previous temperature cable is still connected to the board here, disconnect and remove it. You will no longer need it.

Connect the temperature sensor's two-wire red-black cable to the motherboard plug labeled HD TMP or HDD TEMP.

The connector is keyed to fit in one way only. If it seems like the connector is not fitting the socket, flip the connector and try again.

Route the excess wire so it does not interfere with any other components.