Dem hips. If your hips open well before the club is on its way down your face sits wide open and you create a monster of a slice.
1. get to the top of your swing.
2. drop that right elbow (guessing your right handed) into your pocket
3. power through that sucker for those who claim don't swing hard with a driver you're an idiot. There is no benefit of a driver other than insane distance. If you want control off the tee hit a 3W you wimps