(CNN) -- The new iPad may be a hot item in more ways than one.
In the five days since the popular tablet went on sale, Apple comment boards have filled with anecdotal reports from owners who say the back of the device grows uncomfortably warm to the touch, especially in the bottom left-hand corner when held in portrait mode.
"Both my wife and I upgraded from iPad 1 to the new iPad," wrote a user named dhcwh on Apple's site. "Not happy about the uncomfortable warmth of the new iDud. Not hot, just annoyingly warm. Seriously considering returning both."
"Mine is also getting pretty hot," said another user, malageno, who bought a 32-gigabyte Wi-Fi model. "It's not too hot to hold yet, but it seems to be getting hotter the more it's on."
A user named Limitin added, "My new iPad is also overheating, bottom left like everyone else. The screen is great, but the heat is near unbearable at times and makes my hands sweaty while holding it."
Research by Consumer Reports appears to bear this out. Using a thermal-imaging camera, Consumer Reports engineers recorded temperatures as high as 116 degrees Fahrenheit -- up to 13 degrees higher than the iPad 2 -- on the new iPad while playing a video game, "Infinity Blade II."
In a preliminary review last week, Consumer Reports had said the new iPad "is shaping up to be the best tablet we've ever tested."
Many owners of the third-generation iPad have reported no problems, however. And the issue doesn't seem to have cooled interest in the tablet, which features a sharper screen and a more powerful processor than previous iPads. Apple announced Monday it has already sold more than 3 million of the new devices.
In a statement Tuesday, Apple said, "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."
In its tech specs for the iPad, Apple says the device is not meant to be operated in temperatures greater than 95 degrees Fahrenheit.
Some observers, including an unnamed Apple store employee in suburban Los Angeles, have attributed the warmth to the iPad's new battery, which is larger than in previous models. Others blame the device's larger graphics chip, which helps it run video games.
Some iPad owners said they returned their devices to Apple stores and exchanged them for new ones. Others said the problem went away after they drained the iPad battery completely and then recharged it.
Still others suggested reports of the problem were overblown.
"Personally I think a lot of people are blowing the heat problem ... out of proportion," a user named DaveBLondon said. "Yes it gets hot, but is it too hot that it will burn you? No."
Another user, jimpal, said, "Yes, it's warmer than the previous iPads. But, what would anyone expect with so much going on in there? It has spectacular graphics, is faster, and has a huge battery. Any form of computer runs hotter when it is doing more."
It's not the first time consumers have grumbled about Apple products overheating, especially when used in direct sunlight. Scattered similar complaints surfaced about the original iPad and the iPad 2, which did little to dent their popularity.
Apple has sold more than 55 million iPads since the device went on sale in April 2010.