Battery, Thermal & Display Testing
Battery Test - Tomb Raider 2013 Battery Rundown
To test battery life, we set each laptop’s battery profile to Balanced while running Tomb Raider’s built-in benchmark at the lowest detail preset. The frame rate is locked at 30 FPS through GeForce Experience’s Battery Boost to limit the strain on the battery. Meanwhile, a script running in the background monitors and time stamps the system’s battery percentage. The laptops are set to hibernate once battery levels reach 5%. We test the battery life at 200 nits.
We don't expect particularly great battery life from gaming laptops because GPUs are power hungry, especially the GTX 1080. What happens when you stick two of them in a laptop? Well, the result isn't pretty. Nvidia's Battery Boost technology works by limiting the frame rate, but it doesn't support SLI configurations. Therefore, the GPUs are free to render Tomb Raider's benchmark scenes without limit, which draws more power from the battery. This drains the Acer Predator 21 X's battery faster than usual, resulting in just over an hour of game time. This is about 10 minutes more than the MSI GT73VR Titan SLI 4K's run time, but neither scores are impressive. With SLI disabled, the Acer can muster an additional 20 minutes of game time, which isn't much, but it might be enough time to save your game and shut off the machine. Comparatively, the Titan SLI gains about 35 minutes of additional game time when one of its GTX 1070s is disabled, illustrating just how power-hungry that GTX 1080 is.
Normally, we use our Optris PI 640 infrared camera to measure the laptop’s thermals. However, the Acer Predator 21 X's chassis is incredibly restrictive, and exposing the cooling solution requires an extensive teardown. For cases like these, AIDA64's thermal logging comes in handy. For more information about how we test, be sure to check out our Measurement Science article.
Besides guzzling battery life, the GTX 1080 imposes quite a bit of heat. Luckily, the Predator 21 X's chassis is large enough to house a robust cooling solution. Sort of. One of the GPUs remained cool, even after a 15 minute Furmark stress test. GPU 1 maxed out at 63°, which is the coolest maximum temperature in our comparison set. GPU 2 didn't fare as well; it hit temperatures close to 70°, similarly to the Tornado F5.
We used the SpectraCal C6 Colorimeter to measure the Acer Predator 21 X's display. Be sure to check out our Display Testing Explained article for a full description of our test methodology.
The Predator 21 X's contrast levels are outstanding. At minimum brightness, it has a high white luminance of 20.7897 and a low black luminance of 0.0175, resulting in a high contrast ratio of 1188.2:1. Contrasts at maximum brightness are even better; it sports a white luminance of 470.0452 and a black luminance of 0.3751, resulting in a contrast ratio of 1253:1. These are the highest contrast values we've seen in a display so far.
We've come to find that laptop displays are RGB balanced at lowest brightness but lose their balance as the brightness is raised, and the Predator 21 X is no exception. Red, green, and blue levels start off balanced, but as we raise the brightness, red levels fall while green levels rise, creating a slightly blue tint.
Grayscale accuracy on the Predator's display is just about optimal. A DeltaE 2000 of 3 or below means that inaccuracies are imperceptible, and the Predator scores just above that at 3.352, which won't bother most people. The grayscale inaccuracy only becomes apparent at brightness levels above 60%.
Very rarely do we find a display with a low average grayscale inaccuracy (or put in a positive way: high grayscale accuracy), so we're pleased to find that the Predator's grayscale errors are unnoticeable almost across the board. The areas we're you'll notice them are at 30% brightness, between 50% and 70% brightness, and at full brightness.
The gamma point barely fluctuates; in fact, the chart illustrates an almost flat line hovering around 2.2. The result is a clean image, and points of imbalanced saturation are virtually imperceptible.
The Predator 21 X has a high degree of color accuracy, with a DeltaE 2000 of 3.8347, which will appear accurate to only the most fastidious eyes. The only issues are green and cyan inaccuracies, which are perceptible throughout the brightness scale, and blue, which is only noticeable at full brightness.
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