apple's performance per watt is a remarkable accomplishment. but the second half of your comment has more to do with the anemic thermal design of windows OEMs than anything else. my intel desktop (9700k with 5ghz all-core OC) is also barely audible while running anything less intense than prime95. it just takes a large air cooler with a sensible fan curve. dell could easily do better with a custom case if they actually cared.