Most amateur golfers believe that club head speed comes from swinging the arms faster. They try to accelerate the hands. This leads to a steep angle of attack and an out to in swing path. Resulting in a weak slice. At impact the shaft is leaning away from the target.
The power comes from the unwinding lead by the lower body. This produces a shallow angle of attack and a much straighter swing path. Results are a square face so that the ball starts straight and the straighter path means the ball doesn’t curve.
The next time you watch golf on TV notice that pros at impact have the shaft of the driver leaning forward, toward the target. So swing at the speed that the lower body can move and you will play straighter, longer drives.