It was something we definitely noticed during our Quick Look first impressions of the new iPad: after having the tablet on for even just a short amount of time, the bottom half of the aluminium back chassis felt warm to ours hands. Not hot, but definitely warm enough to warrant notice and even a little bit of concern. Turns out, plenty of other users noticed the same thing, and enough complained for Apple to issue an official statement, via its PR representatives:
The new iPad delivers a stunning Retina display, A5X chip, support for 4G LTE plus 10 hours of battery life, all while operating well within our thermal specifications. If customers have any concerns they should contact AppleCare.
Armed with an infrared thermometer in hand, I set out test the temperature differences between all three generations of iPads, along with the iPhone 4S. The test conditions for all devices were set to be as identical as possible--unplugged, screen set medium brightness, auto-lock turned off, Wi-Fi on, and volume set to low. I measured the temperature of each device's back using the thermometer at a close distance after the following situations:
- All devices turned off for half an hour to start, with a full charge in their batteries.
- Five minutes of idling at the home screen.
- 10 minutes of browsing the web, scrolling through pages and clicking the same links.
- 10 minutes of full-screen video playback of a YouTube video in landscape orientation.
- 15 minutes of playing Infinity Blade II.
Ambient room temperate was a cool 67 degrees Fahrenheit during the duration of the test. In the results, I noticed that the temperature differed depending on where on the back I pointed the thermometer. The results below are of the highest recorded temperature, which for the new iPad was on the bottom right hand corner of the back. All results are in Fahrenheit.
|Test Situation||iPad (1st gen)||iPad 2||iPad (3rd gen)||iPhone 4S|
|Idle at Home Screen||70||70||71||71.5|
|Infinity Blade II||73||78||82||81|
The upshot is that the new iPad is warmer than previous models, especially in a processor-intensive app like Infinity Blade II, but my test didn't show a worrying temperature delta, like some other reports. It certainly never passed 100 degrees Fahrenheit at any time during my use. Yes, it's warmer, but that can be attributed to a battery that has almost twice the power capacity of the last generation, not necessarily a physical design fault. For other owners of the new iPad out there, how does it feel in your hand after extended use? And what are the apps that you find make it warm up the quickest?
Update: Dr. Raymond Soneira of Displaymate reached out to us with this explanation for the temperature difference:
The new iPad Backlight consumes 2.5 times as much Backlight power as the iPad 2 for the same brightness (Luminance). This is due to the high ppi, which makes the LCD have a lot lower light efficiency and therefore power efficiency. It has 72-82 LEDs, roughly double the number of LEDs as the iPad 2. The LEDs give off 2.5 times as much heat as the iPad 2 and so will the battery and power electronics on the new iPad compared to the iPad 2.
When the display is set for maximum brightness the display consumes about 65% of the total new iPad power, so it plays a major role in the thermal budget. At the medium slider setting the Backlight consumes only 36% as much power as at maximum, so that is only 36% of the heat also.
Additional note: I haven't taken screenshots of Infinity Blade II yet, but I'm now almost certain that that game renders at a lower than native resolution, and then is upscaled to 2048x1536. The difference between the visuals of the game on the new iPad and first-gen iPad, along with framerate, is nevertheless astounding.