Pro Max figures
Apple used a larger vapor chamber with the 2 nm A20 Pro chip in the iPhone 18 Pro and Pro Max. The internal design was changed so that the chip made contact with the chamber.
Pro Max measurements
However, in The Tech Chap’s 10-minute gaming test, the iPhone 16 Pro Max measured 42.9 °C, the iPhone 17 Pro Max 38.7 °C, and the iPhone 18 Pro Max 37.2 °C. In Geekerwan’s comparison, the iPhone 18 Pro Max recorded 44.3 °C at 5.9 W of power; the OnePlus 15, 47.2 °C at 6.1 W; and the iQOO 15 Ultra, 47.2 °C at 5.9 W with the fan off and 46.2 °C at 7.3 W with it on. The purpose of the vapor chamber is to distribute heat evenly and preserve performance; the results show that the iPhone remained stable at a lower temperature.