The OnePlus Nord 4 does one thing better than any other Android phone

Other than a few deviations, OnePlus has a penchant for value products. The premium OnePlus 12 offers a (mostly) superior set of features and a refined experience over similarly-priced flagships such as the Galaxy S24 Plus or the Pixel 8 Pro. Similarly, the $500 OnePlus 12R offers exceptional performance and a flagship-like experience for its price. The OnePlus Nord 4, which sits in a price bracket right under the 12R, has its own benefits, but one that stands out is its metal back.

The OnePlus Nord 4 is the first and currently the only 5G phone to feature a metal back panel. Not only is it a striking design but it also has another trait that perceivably makes it more exciting than other phones: Its metal body potentially helps improve performance.

Metal is a better conductor of heat than glass or plastic and is superior at radiating heat outward — meaning the Nord 4 should run cooler than other phones. The effectiveness at cooling is also expected to complement the chipset driving the Nord 4 (the Snapdragon 7 Plus Gen 3). Despite being a victim of Qualcomm’s confusing naming, the Snapdragon 7 Plus Gen 3 is potent enough to run most demanding tasks and is likely geared to run AI applications in the future.

So, does the Nord 4’s metal back help its Snapdragon chip run better and cooler? I found out.

How I tested Nord 4’s cooling

The biggest perceived benefit of the metal back when it comes to gaming. In addition to the vapor cooling chamber inside the phone, the metal back helps radiate inner heat generated from the chipset or the battery — the two primary sources of heat inside the phone. I played around (literally) with the OnePlus Nord 4 extensively to see if the theory holds up in practice.

To evaluate the metal back’s effects on the Nord 4’s performance, I set out to test how effectively it prevents heat buildup inside the body. The evaluation was divided into three parts, or potential contributors of heat generation and trapping inside the phone. Other than gaming, I also tested challenging scenarios, such as 4K video recording and high-speed charging, that can lead to the phone getting hot.

For each of these tests, I ran the tasks for 30 minutes to let the heat build up inside the body and on the surface. After the completion of each task, I waited for the phone to cool down to the original temperatures using an infrared thermal camera and noted the time taken in each case. Here’s how the tests panned out.

Heating while 4K video recording

Video recording constantly engages multiple parts, which, besides the camera itself, include the phone’s chipset, storage, and image signal processor (ISP). The display being constantly engaged is yet another reason for the hardware to feel burdened — and, therefore, heat up as a result. So, for my analysis, I set the OnePlus Nord 4 to record a 4K video at 60 frames per second. The rest of the settings, such as white balance, were left to automatic. Although the video was shot indoors, my dog contributed to some reasonable motion capturing and, as a result, occasional refocusing of the sensor.

The video was shot in an air-conditioned room, despite which the phone’s external surface heated up significantly. After I ended the recording, I left the phone to cool down. Here are my primary findings:

• Ambient temperature: 82 degrees Fahrenheit
• Starting temperature (before video recording): 88 degrees F
• Temperature after 30 minutes: 102 degrees F
• Time taken to return to original temperature: 17 minutes

While the 17-minute span may seem harrowing, the warmth subsided within five minutes, and the phone started to feel cold.

How cool is fast charging?

The Nord 4 charges at 100W, which is commendably fast. Although the phone charges fully within 35 to 40 minutes, that warrants some heat generation in the process. I followed a similar process as the last time but with one key change. The phone was charged and subsequently left to cool down without any air conditioning.

Here is what I found out:

• Ambient temperature: 91 degrees Fahrenheit
• Starting temperature: 95 degrees F
• Temperature after 30 minutes: 104 degrees F
• Time taken to return to original temperature: 28 minutes

It took longer to return to its original temperature (which still seemed dangerous due to the warm room). However, to my surprise, the warm room did not significantly slow down charging as I thought it would. Perhaps it would if the phone reached temperatures in the range of 120 degrees or higher, which, thankfully, it didn’t.

This also goes on to back my initial hypothesis that a metal back would cool faster in an air-conditioned room than one without. But to confirm my findings, I ran an extensive series of tests with variations to see how each affects the Nord 4.

The Nord 4’s ultimate test — gaming

Gaming is easily one of the most demanding tasks for a phone. Additionally, its propensity to heat is bound to increase if the hardware struggles to keep up with the demands of the game — and that is what makes the Nord 4, a non-flagship phone, the ideal candidate to study the effects of heating.

For this series of tests, I ran one of the graphically heaviest cross-platform games, Genshin Impact, at the Highest graphics settings with textures set to High and the intended frame rate set to 60 fps. These settings make the best of hardware sweat, so testing how the Nord 4 holds up would have given us the insights we were looking for.

Besides turning to the highest settings, I also used OnePlus’ own HyperHDR feature that upscales standard content to HDR for better visibility, especially in darker scenes. But it also increases the brightness and, therefore, demands more of the phone’s hardware.

In addition to the temperatures, I recorded the Nord 4’s performance using GameBench, a professional game-benchmarking tool. I must disclose that while GameBench helped me with a free journalists’ license for the app’s Pro version, it did not have input on my findings.

The test is subdivided into four parts, adding one attribute at a time to help consolidate the findings better.

Part 1

The first one begins with me running Genshin Impact on the Nord 4 through its paces but in an air-conditioned ambiance. This would allow the phone to cool effectively while I game and then leave the phone to cool down. Here are my findings from the test:

• Ambient temperature: 82 degrees Fahrenheit
• Starting temperature: 86 degrees F
• Temperature after 30 minutes: 104 degrees F
• Time taken to return to original temperature: 13 minutes

Interestingly, the phone cooled more effectively than it did in the case 4K recording test I ran above, further solidifying my belief that a cooled environment can improve its cooling. For most of the time, the phone remained warm to the touch but never got uncomfortably hot. The internal temperature of the CPU, as per GameBench, stayed around 108 degrees F, which doesn’t show a significant difference from the temperature at the external surface.

While playing, the game consistently ran without any notable stutters. GameBench identified it to deliver a consistent 57 frames per second over the course of 30 minutes, with the occasional frame drops attributed to cooking meals, cutscenes while speaking to unplayable characters, and loading screens.

Part 2

For the next part, I tested without any external cooling. I played the game on the OnePlus Nord 4 while sitting in a room without AC to see how hot the phone gets.

As I noted in Part 1 of this test, the Nord 4’s external temperature fairly matches its internal temperature. So, I expected it to heat up much more without releasing heat due to sitting in a hotter room. But I was surprised when the phone got significantly hotter than usual.

• Ambient temperature: 91 degrees Fahrenheit
• Starting temperature: 96 degrees F
• Temperature after 30 minutes: 113 degrees F
• Time taken to return to original temperature: 25 minutes

About 15 minutes into the game, the Nord 4 started to heat up significantly. It reached a temperature that I would prefer my hot shower to be at on a cold day. While I could endure the heat because it was still short of scalding, I would prefer not to comply. At the end of the 30 minutes, I was glad it was over.

During most of the gameplay, the internal temperatures floated around 120 degrees Fahrenheit, so the outward channeling was expected. With temperatures soaring so high, the Nord 4 also threw a warning while turning off the HyperHDR feature. Findings from this part prompted me to change one more bit about this test.

Part 3

In this part, I played the game without air conditioning but set the phone to cool down in an air-conditioned room, assuming that if my theory was accurate, it would help the phone cool faster despite the higher temperature.

Once again, the phone got disadvantageously hot. But setting it down in a cooler room than used to play the game really helped speed up the cooling process. Here’s what I found out:

• Starting ambient temperature: 91 degrees Fahrenheit
• Cooling ambient temperature: 82 degrees F
• Starting temperature: 96 degrees F
• Temperature after 30 minutes: 113 degrees F
• Time taken to return to original temperature: 10 minutes
• Time taken to return to cool down completely: 20 minutes

In the AC room, the Nord 4 returned to a cooler temperature five minutes earlier than the last test. In fact, it achieved its initial temperature in under 10 minutes, finally returning to 88 degrees in about 20 minutes of total time.

By now, I was pretty convinced my theory holds. But I couldn’t conclude without one final test — involving materials other than glass.

Part 4

For the last and final part of my gaming test, I roped in two more phones other than the OnePlus Nord 4. The duo includes the Realme GT 6, which comes with a plastic back and frame made out of plastic. It runs the Snapdragon 8s Gen 3, a chip comparable to the Nord 4’s Snapdragon 7 Plus Gen 3. Besides the Realme with a plastic back, I chose the OnePlus 12R with a glass back and metal side frame. Although the OnePlus 12R runs a more powerful Snapdragon 8 Gen 2 chip, I chose it for the lack of a glass phone with performance matching the other two. All of these phones were tested with air conditioning to inspect how quickly each material cools.

The following summarizes the findings from running the same instance of Genshin Impact on the three phones:

The results couldn’t be clearer and show a convincing picture of the Nord 4’s ability to dissipate heat better than the other two devices. The Realme GT 6, with a plastic back, retains the most heat internally and takes the longest to return to its original temperature. The OnePlus 12R understandably generated less heat internally as the more powerful chipset requires less effort to achieve the same performance. However, it also traps a significant amount of heat inside the body, taking only slightly less time to cool down.

Had an external cooling source been absent, we can imagine the Nord 4 to feel the hottest while the other two devices would trap more heat inside and throttle as a result.

The Nord 4’s metal back really works

While I admit the method I use above is not typically the stuff from science labs and academic journals, it gets the point across fairly well. It clearly conveys that metal helps effective cooling of the smartphone, especially when using it for demanding tasks such as gaming.

The OnePlus Nord 4’s metal casing acts as a large radiator for the tiny CPU, and I can’t help but draw a parallel with a PC that uses a passive cooler much bigger than the CPU. Of course, an active cooling solution such as a fan — either built-in or as an accessory — would highly amp up the cooling spree. Notably, while I tried out the black edition, the phone’s color may also have an effect on its cooling. The No. 1 reason why that may happen is because black is better at radiating heat to the atmosphere than any other color. The second reason applies more specifically to the Nord 4, whose silver finish has microscopic textures that give it a wave-like pattern.

Meanwhile, heat buildup inside other devices can not only throttle performance but also risk the internals getting cooked, especially if you tend to overclock game settings on midrange phones. This demands more effective cooling solutions beyond the now plateauing vapor cooling chambers, and this is where metal becomes effective.

Simultaneously, there are drawbacks to metal constructions that we can’t ignore. Firstly, it can obstruct 5G signals — even though OnePlus has seemingly found a cure by cutting down the size and upping the number of antennas. Secondly, the phone is bound to heat up more when used outdoors, in the sun, and this can be especially tiresome while traveling to hotter places. Thirdly, it limits features such as wireless charging and hinders functions like MagSafe, which is why we may not see metal replacing glass on more expensive phones.

For all it’s worth, though, metal, coupled with increasingly powerful midrange chips, can be a breakthrough in phone performance, as we see on the OnePlus Nord 4.