Thermal Considerations

Thermal performance has always been an important topic when it comes to mobile processors, but in the past few years, it has become paramount. With the increasing demand from consumers for notebooks to be thinner and lighter, one of the things that grows more difficult to solve is how to dissipate the heat generated from power hungry components such as the CPU and the GPU.

Intel and others have attempted to alleviate this issue by allowing OEMs to configure the power draw of their processors in specific scenarios to make sure that their cooling solutions are adequate to the specifications for the given notebook model.

Taking the dramatically different form-factors of these two notebooks into account, we decided to take a closer look at their thermal solutions.

For our thermal testing, we ran the x264 benchmark. This application uses the popular x264 video encoder to transcode a 1080p video while measuring the average FPS of the process. More importantly for this test, the encode runs the same test four times in a row, allowing us to easily measure scores over time.

Taking a look at Pass 1 (the first of two parts of the encoding workflow), we see that while the ZenBook 3 slightly outperforms the Spectre in the first iteration of the test, the performance quickly drops off in subsequent runs. 

We can also see this effect in Pass 2, which is the more CPU-intensive part of the encoding process.

Looking at the benchmark results, it's clear that the thin-and-light design of the ZenBook 3 means that it's struggling to keep up with the Spectre x360 under heavy load over an extended amount of time.

We can see this trend continue by taking a look at the CPU frequency, power consumption, and temperature over this same test, measured using the Intel Power Gadget software.

Taking a look at the CPU frequency throughout the test, we see a high spike in speed during the first 100 seconds or so from both machines, but the ZenBook 3 manages to maintain higher clock speeds for longer than the Spectre. However, as the test continues, the Spectre x360 consistently runs at a higher clock speed than the Zenbook.

This continues throughout the temperature and power consumption measurements. Past its initial burst, the ZenBook 3 consistently is hotter and uses less of the available 15W TDP (as it needs to cool down the components slightly) than the Spectre for lower performance levels.

If you compare this to both our standard notebook benchmark test results and our x264 results, this starts to make sense. The ZenBook 3 Deluxe's cooling system and processor configuration are tuned to deliver a burst of high performance when you begin a workload but eventually succumbs to heat.

Potential thermal design issues were also evident in the relative fan speed and surface temperature differences in using the ZenBook and the Spectre. While the ZenBook's fan was often spinning fast and the device was hot during normal use, the Spectre's cooling system seemed to be better equipped to handle it.

These thermal differences aren't necessarily a negative with the ZenBook design or a positive with the Spectre x360 design; rather it depends on your given workloads. For users who are doing intensive tasks that don't take an extended amount of time to complete, such as image editing in Photoshop or heavy spreadsheet work in Excel, the ZenBook 3 is at an advantage for users looking for a thin-and-light design.

If you are editing video or compiling large applications, the HP Spectre x360 would be a better option. The new quad-core 8th generation CPUs allow you to work done faster than their dual-core predecessors, but you gain the battery life and portability advantages of a notebook with a 15W CPU as opposed to the previous 35W quad-core entry-level processors.

It's clear that with the release of Intel's 8th Generation Core processors and AMD's recent announcement of their Raven Ridge APUs, the thin-and-light notebook market is going through a considerable change.

Stay tuned for more information and testing as we get our hands on more of these machines in the coming weeks!

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