There were warnings from the look-outs.

At a slower speed the officer on the bridge would have had more time for his corrective measures to work (reversing engines, jamming the tiller to the right to move the ship to the left). Even if the look-outs had not seen the berg sooner. Obviously, with a couple of minutes more of warning and at a slower speed, the impact would not have been as great and if the ship were 20 - 30 feet further away from the berg, it would not have penetrated the ship as deeply and popped the seam of rivets through as many watertight compartments.