This September, Apple surprised many by swapping titanium for aluminum in its flagship iPhone 17 Pro and Pro Max models — a notable change after only two years of titanium use starting from the iPhone 15 Pro. Interestingly, Apple did not return to stainless steel either, opting instead for aluminum bodies across all new models except the Air. This shift was driven by one key goal: improved heat management.
With the debut of Apple’s powerful A17 Pro chip, fabricated using 3 nm technology, users quickly noticed that while performance was impressive initially, overheating and thermal throttling significantly limited sustained usage—especially during gaming and intensive video tasks. Apple aimed to tackle this challenge through redesigned materials and cooling methods.
From my perspective, stainless steel would have provided a better middle ground than aluminum. Though titanium offers excellent durability and lightness, its thermal conductivity lags behind aluminum and stainless steel. Moreover, the polished stainless steel frames of past Pro models boasted sleek looks, despite being prone to fingerprints and smudges. The new aluminum bodies, by contrast, seem more susceptible to chips and dents.
However, Apple also introduced a new vapor cooling chamber — a feature that has been commonplace in many Android flagships, pioneered by brands like Asus and Samsung. This internal vapor chamber contains a small amount of liquid that evaporates near the hot processor, moves away to cooler areas, releases heat by condensation, and transfers warmth to the metal chassis. This method enhances overall heat dissipation.
The Impact of Aluminum and Vapor Cooling on Performance
Benchmark comparisons clearly indicate the thermal advantages aluminum brings. The iPhone 17 Pro throttles later and sustains higher performance scores compared to the titanium-bodied iPhone 16 Pro.
| 3DMark Extreme (High) Higher is better |
Apple iPhone 17 Pro – 5914
Apple iPhone 16 Pro – 4479
|
| 3DMark Extreme (Low) Higher is better |
Apple iPhone 17 Pro – 3506
Apple iPhone 16 Pro – 2383
|
Images from cycle 3 of the benchmark reveal that while the iPhone 16 Pro stabilizes at lower performance levels early on, the iPhone 17 Pro continues pushing higher scores longer.
FLIR Thermal Imaging: How Aluminum Helps Manage Heat
To visually verify these temperature differences, we used a FLIR thermal camera to compare the iPhone 16 Pro (titanium body) and iPhone 17 Pro (aluminum body) under various states.
Idle Temperatures
After 20 minutes of idle time, both models showed similar baseline temperatures, indicating comparable heat retention when not in use.
3 Minutes Into Stress Test
Running the 3DMark Wildlife Extreme Stress Test, the iPhone 16 Pro showed a hot spot concentrated near the volume keys reaching around 41°C, while the surrounding chassis remained cooler. The titanium frame didn’t effectively spread this heat outward.
In contrast, the iPhone 17 Pro’s aluminum body distributed heat more evenly across the chassis, with peak temperatures around 36°C — about 5 degrees cooler at the hottest spot than the titanium model at this stage.
10 Minutes Into Stress Test
After sustained stress, the iPhone 16 Pro’s hot spot temperature rose to roughly 45°C, an uncomfortable level for prolonged hand contact, though the heat remained localized.
The iPhone 17 Pro warmed to about 42°C across its frame, but with heat dispersed more uniformly, resulting in a less intense localized hot spot and a more balanced heat profile.
After Cooling Down
Five minutes post-stress, both devices cooled to similar temperatures near 36°C. The iPhone 16 Pro’s localized heat had spread, and the aluminum iPhone 17 Pro remained evenly warm. Ten minutes later, neither phone had returned fully to idle temperature, but neither displayed advantages in cooling speed.
Conclusion
Switching from titanium to aluminum for the iPhone 17 Pro line clearly aids in spreading heat away from key hotspots during heavy use. The aluminum frame paired with the new vapor cooling chamber delays thermal throttling and sustains performance better than the titanium predecessor.
However, the aluminum build does result in a warmer-feeling frame during intensive tasks because the heat isn’t localized. In standby or light use, the cooling characteristics between the two materials appear similar. For users seeking the best sustained performance and heat management, Apple’s aluminum-bodied iPhone 17 Pro represents a meaningful step forward.
