You can’t have missed the reports that certain iPhone 15 Pro series phones have been found to overheat. People have been complaining about hot-running Pro models since they launched.

Now, analyst Ming-Chi Kuo has released a note, concluding that the A17 Pro chipset isn’t to blame for the overheating but rather compromises Apple made in the design of the thermal system. The A17 Pro is built on TSMC’s advanced new 3nm node, which is very efficient, but apparently still outputs more heat than the phone can dissipate.

In this case, Apple’s efforts to make the new iPhone Pro models lighter are to blame. Due to the higher heat conductivity of titanium, Apple had to reduce the heat dissipation area, resulting in worse heat management.

Throttling issues will likely be addressed by Apple with a software update, which can manage but not fix the issue. By limiting a phone’s performance and power requirements, a software update can prevent overheating.

It isn’t entirely clear why only some of the phones are affected by Kuo’s theory.