It's clear HP decided to let performance fall off rather than subject you to searing temps. I re-ran our encoding test at one hour in and recorded the highest temperature at 118 degrees Fahrenheit on the hottest point on back. At the same time with the XPS 13, I saw a similar 118 degrees in one spot of the laptop.
On the keyboard, though, the Dell would hit 109 degrees on part of it, with part of the hinge reaching 125 degrees. The hottest the HP would get is 100 degrees. Such a throttling hit isn't huge (I'm actually seeing far more in another laptop I'm testing), but it goes counter to HP's brag that the Spectre x360 offers the "best performance" possible. Perhaps the company should have said: "Best performance possible while balancing user experience in fan noise or skin temp." That I'd buy.
Impressive battery life
The good news for the Spectre x360 is its impressive battery life. The unit features a big 56-watt-hour battery, compared to the Dell's 52-watt-hour pack. HP says it also intentionally chose an IPS panel with PSR (panel self refresh technology). PSR works by essentially shutting off the graphics output as well as the embedded DisplayPort link to the panel.
The result: The Spectre x360 offers 1:45 more run time over the XPS 13, which uses a high-resolution, 3200x1800-pixel screen. Dell says that panel is IGZO-based, so it's more power-efficient than a typical IPS high-res panel; however, IGZO can't compensate for its 5.7 million pixels vs. the 2 million pixels in the HP. Only the Dell XPS 13 with the lower-resolution 1920x1080 panel beats the Spectre x360. (That model of the XPS 13 also lacks a touchscreen, another battery suck.)
The screen itself is quite gorgeous. It didn't exhibit excessive leakage nor compression banding. As a ten-point touchscreen, it's glass and and naturally reflective, which I've come to expect. It's beautiful, but at times it felt too reflective. The touchscreen is directly bonded to the panel, though, which brings the pixels as close to you as possible.
There's a lot to like in the Spectre x360. It offers a convertible's versatility and great "lapability." It's also flat-out gorgeous with its polished aluminum edges. The keyboard alone makes it superior to the Dell XPS 13.
But--and you knew the 'but' was coming--it's not the lightest convertible at 3.3 lbs, nor the smallest. I also nit-pick that HP sexed up everything about the Spectre x360 except the power brick, which is the same brick you'd get with the company's $199 Streambook! Even the company's drop-dead-gorgeous Omen used one boring block of a power supply. I know there's something to be said for uniform power bricks from the same company, but with the Spectre x360, it feels like you have a Rolls Royce with Yugo tires.
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