iPhone 7
Several iPhone 7 units are reportedly affected with hissing sound when under peak usage

Several iPhone 7 and 7 Plus owners are facing unexpected hardware problems within 24 hours after the release of Apple's new flagship phones. The issue was initially spotted by Stephen Heckett of 512 Pixels as he reported some iPhone 7 units making a hissing noise while under heavy processor load.

According to 9to5Mac, there have been confirmed reports with several users facing the same issue while using the new iPhones.

It is ascertained that the issue is linked to Apple's new A10 Fusion chip as the sound appears to be coming from the rear of the device near the Apple logo where the chip is located. Furthermore, the hissing noise is heard only when the device is under peak load or heavy processor usage.

Check out the hissing sound emanating from the iPhone 7 Plus under heavy load, in the following video uploaded by Heckett:

It is still unclear if the issue is widespread or persists on both the iPhone 7 and 7 Plus models or if only one of them is the culprit. As the new iPhones do not have a processor fan or cooling fans on the chip, any possibility of fan noise resulting in the hissing sound is ruled out.

Apple's new flagship phones use two performance-optimised cores and two energy-efficient-optimised cores on their quad-core A10 Fusion chip, which allows the handsets to save power while dynamically switching between energy-efficient and performance cores.

It is assumed that Apple might fix the hissing sound with a firmware update. However, Apple's customer support is presently asking affected users to ship the defective handset for a replacement via Apple Store, suggesting it could be a hardware problem.

Anxious users who would like to test their iPhone for the hissing sound can try playing a graphics intensive game or run Geekbench 4.0 for straining the iPhone's internal components.

Here are a few interesting comments from existing iPhone 7 owners who are facing this problem:

iPhone 7 hardware problems
iPhone 7 users report 'hissing' sound under heavy processor load Twitter