Ahead of its October 23 retail debut, Apple's foldable iPhone Duo has become a test of a familiar tension in modern gadgetry: how much heat a thin, folding machine can carry before comfort and performance begin to give way. Reviewers have split along the lines of how hard they pushed it, with long calls, extended camera work and sustained gaming revealing warmth that some found tolerable and others found hard to ignore. Whether this proves a rare limit or a lasting trait of the design will be settled not by the press but by the quieter, longer lives of the people who now carry it.
iPhone Duo Reviews Split on Heat: Some Testers Report Discomfort and Throttling, Others Find Cooling Adequate
A system can pull heat off the chip and still leave the phone hot to hold.
Mark
Why did Stern's hung-up FaceTime call stick with people?
Mimi
Because it's concrete. Apple said the heat means the cooling works, and she said it still felt like holding a very hot phone. Both can be true.
Luke
But it's one reviewer's experience. We don't know how many units behave that way.
Mark
What's different about the Duo's cooling?
Mimi
Same kind of vapor chamber as the iPhone 18 Pro series, but thinner. Apple added a flexible graphite heat pipe around the hinge to move heat between the two halves.
Mark
And the test numbers?
Mimi
HTX Studio saw 46.5 degrees Celsius after 30 minutes of gaming, versus 43.8 for the 18 Pro and 43.2 for the Pro Max. Frame rates were about 20% lower and brightness fell to 185 nits.
Luke
That's one lab's test. Mrwhosetheboss found the gap with the Pro Max wasn't easily noticeable in ordinary use, and Gizmodo saw no significant throttling.
Mark
So is it a problem?
Mimi
It seems to depend on what you do. Long gaming, video calls and camera use are where complaints cluster.
Luke
And the article itself says differences may come from test length, environment and measurement methods. Whether it's widespread is unknown until real customers weigh in after October 23.
Il Polso
- A reviewer hangs up a FaceTime call because the phone's back has become too hot to hold, turning a spec-sheet concern into a very personal discomfort.
- Apple's explanation that the cooling system is simply doing its job meets skepticism, since moving heat off the chip does not guarantee a device that feels pleasant in the hand.
- A thinner vapor chamber and a graphite heat pipe around the hinge are Apple's attempt to steer heat across two halves and two displays in a cramped interior.
- Lab numbers diverge sharply: one test records 46.5°C, roughly 20% lower frame rates and brightness dropping to 185 nits, while others report only mild warmth and stable performance.
- With sales now open, the device heads into everyday use, where the real verdict on whether the heat is an occasional annoyance or a widespread complaint will be written.
Ahead of its October 23 retail debut, Apple's foldable iPhone Duo has become a test of a familiar tension in modern gadgetry: how much heat a thin, folding machine can carry before comfort and performance begin to give way. Reviewers have split along the lines of how hard they pushed it, with long calls, extended camera work and sustained gaming revealing warmth that some found tolerable and others found hard to ignore. Whether this proves a rare limit or a lasting trait of the design will be settled not by the press but by the quieter, longer lives of the people who now carry it.
Partway through a FaceTime call, technology journalist Joanna Stern hung up. The back of Apple's iPhone Duo had grown so hot in her hand that she could not comfortably keep talking. It was one of the most vivid moments in a batch of reviews published ahead of the foldable's October 23 retail launch, and it placed heat management at the center of the early conversation.
When Stern raised the issue with Apple, the company said the cooling system was working as intended, moving heat away from the processor to keep performance steady. She was not fully persuaded. A system can pull heat off the chip and still leave the device uncomfortable to hold.
The engineering explains part of the tension. The Duo uses Apple's A20 Pro and a thinner custom vapor chamber, with a flexible graphite heat pipe around the hinge to spread heat between its two halves. Limited space, two displays and the hinge make cooling harder than in a conventional phone.
Reviewers reached different conclusions. Some found the device ran warm during extended camera use and gaming, with occasional stutter and lag. Others measured the gap as modest, or found heat spread evenly and performance holding up, with Gizmodo judging the vapor chamber effective. The differences may reflect workload, test length and how temperature was measured. The concerns cluster around long sessions; people who mostly browse or message may notice little. Now that sales have begun, everyday owners will determine whether the warmth is an occasional limit or a common complaint.
Partway through a FaceTime call, technology journalist Joanna Stern hung up. The back of Apple's iPhone Duo had grown so hot in her hand that she decided to end the call. It was one of the more vivid moments in a batch of reviews published ahead of the foldable's October 23 retail launch, and it put thermal management at the center of the early conversation about the device.
When Stern raised the heat with Apple, the company told her it was the cooling system doing its job: moving heat away from the processor to keep performance steady. She wasn't fully persuaded. She conceded that Apple might see the warmth as a sign of effective heat transfer, but said the experience was still that of holding a very hot phone. A system can pull heat off the chip and still leave the device uncomfortable to hold.
The engineering explains part of the problem. The iPhone Duo runs on Apple's A20 Pro processor and a custom vapor chamber similar to the one in the iPhone 18 Pro series, but the foldable's chamber is thinner. To compensate, Apple added a flexible graphite heat pipe around the hinge, which moves heat between the two halves and gives it more surface area to escape. Limited internal space, two displays and the hinge all make cooling harder than in a conventional slab phone.
Some reviewers say the system cannot fully contain the heat. The Verge reported that the device got hot during extended camera use, especially with both displays active through features such as Duo Preview, and that prolonged use could bring stuttering and lag. It saw similar behavior in some third-party apps, notably video apps and Google software, suggesting the problem is not confined to graphics-heavy games. PetaPixel said its review unit warmed during gaming and photo editing, with the heat gathered on the right side when the phone was fully unfolded.
The numbers vary by test. The YouTube channel Mrwhosetheboss ran a 20-minute sustained workload comparing the Duo with the iPhone 18 Pro Max. The foldable retained more heat when closed and performed worse than the Pro Max, though the gap was not large enough to be easily noticed in ordinary use. HTX Studio found a wider split in a 30-minute gaming test. The Duo reached 46.5 degrees Celsius, against 43.8 for the iPhone 18 Pro and 43.2 for the 18 Pro Max. Its frame rates ran roughly 20% lower than the Pro models, and screen brightness fell to 185 nits instead of the expected 300.
Other outlets were more relaxed. 9to5Mac found the Duo slightly hotter than the iPhone 18 Pro with no substantial effect on performance. Tom's Guide measured temperatures during benchmarks and saw heat spread fairly evenly across the device, though it still ran several degrees hotter than Samsung's Galaxy Z Fold8, the comparison phone. In the 3DMark stability test the Duo scored 75.9%, below the 18 Pro Max's 79% but above the Fold8's 72%. Gizmodo did not see temperature as a major concern and judged the vapor chamber effective, saying it prevented significant stuttering or throttling even with all CPU and GPU cores under heavy load.
The differences may come from workload, test length, room conditions and how temperature is measured. A phone can handle everyday tasks well and still get hot in long gaming or camera sessions, and a hot surface does not by itself mean a performance problem if the processor stays stable.
The concerns cluster around sustained use: long gaming sessions, extended video calls and prolonged camera work. People who mostly browse, message or watch short videos may notice little. With sales now beginning, wider customer experience should show whether the heat is an occasional limit or a common complaint.
Citazioni salienti
Apple told her the heat showed the cooling system working as designed, moving heat away from the processor; she said it still felt like holding a very hot phone.— Joanna Stern, technology journalist, relaying Apple's explanation
Vuoi la storia completa?
Leggi l'originale su Báo VietNamNet ↗
Technology