The reality is that Sony has done a pretty good job here. We'll get to the metrics in a moment, but first impressions are certainly reassuring. On start-up, the hardware is exceptionally quiet, but as you progress into gameplay, volume and heat does start to increase. PS4 also draws a fair amount of juice too - 80W at idle on the front-end menus (the "PlayStation Dynamic Menu" to give it its proper name), 95W based on in-game video playback, and around 110-120W during gameplay - that's about 10-20W more than the first release of the "Slim" PlayStation 3. Curiously though, bringing up the menu system while in-game sees another leap in power draw - up to the maximum of 140W.
The figures sound meaty but the reality is that PlayStation 4 remains fairly discreet throughout general gaming - easily quieter than a launch PS3 overall, but not quite as unobtrusive as the latest PS3 Super Slim model (when its Blu-ray drive is inactive, at least). Only when you run a game and then move to the menus does the system start to kick out some serious heat. We measured 50-degrees Celsius venting from the rear (better out than in, we say) with the casing itself heating up to 45 degrees - that's approaching launch PS3 territory.