Almost-Stock Android And Some Unique Settings
As with Shield, Nvidia's packages its own version of Android with the Tegra Note 7. The company refers to this as "stock Android," and although it's close, the operating system isn't entirely stock in the same sense that Nexus devices run stock Android.
From a user standpoint, the version of Android on Tegra Note 7 looks and behaves very much like the base Android environment. However, its updates come from Nvidia instead of Google, which means it'll always be slightly behind the Nexus update schedule. Case in point, the Tegra Note 7 ships with Android 4.2.2, though Nvidia tells us that an OTA update to 4.3 is currently targeted for December. Today, Android 4.4 (KitKat) is running on the Nexus 5, and by next month the Nexus 4, Nexus 7, and Nexus 10 will all be on the new version.
Semantics aside, we're not docking points for Nvidia's Note not being as current as the Google-supported devices. My personal tastes steer me clear of the custom UI and features implemented by manufacturers trying to cultivate their own brand. The clean and uncluttered implementation you get with the Tegra Note 7 benefits the user in its standardized look and efficiency, while Nvidia can push updates out much quicker with minimal customization efforts.
With that said, there are a few device-specific additions worth talking about. In the settings is a Power Savings menu that we didn't see on Shield. Inside, you'll find a toggle to enable or disable Nvidia's PRISM (Pixel Rendering Intensity and Saturation Management) technology, change processor behavior, and manage nSaver.
PRISM, which now unfortunately shares a name with the NSA surveillance program, is a Tegra-specific feature introduced last generation that can also be found on the 2012 Nexus 7. Nvidia tells us PRISM is enabled on Shield as well. But on Tegra Note 7, it can also be turned off if you so wish. According to Nvidia, "PRISM reduces display power consumption by reducing backlight brightness while dynamically increasing pixel intensity." It's important to note that this feature is completely separate from auto-brightness, which adjusts according to ambient lighting rather than what's on-screen.
In practice, I find PRISM to be a little distracting, as the shift between light and dark scenes on-screen, even while browsing, causes distinct changes in brightness. While this is the feature working as intended, I prefer to set the brightness to a static level and leave it there. Thankfully, Nvidia gives us complete control over the feature. So, anyone looking to really optimize battery life can leave it on. And, in fact, our battery tests demonstrate that PRISM does extend up-time in a pretty spectacular way.
There's also a processor setting that lets you switch between three modes: Maximum Performance, Balance, and Save Battery. The screenshots above and below illustrate how each setting differs. In our testing, there was no discernible performance delta between Maximum Performance and Balance under load, though halving the cores in Save Battery mode definitely has an impact on speed and battery life.
In our conversations with Nvidia about our findings, we learned that the Balance mode responds to utilization by ramping the SoC's frequency up and down. For example, if Tegra 4's processor cores are fully utilized, and the current clock rate is lower than peak, it scales up to its 1.8 GHz ceiling until utilization falls. By then backing off, Balance mode helps increase battery life in more casual use cases like video playback, reading, and even light gaming.
Finally, there's the nSaver feature, which allows you to individually control background activity on an app-by-app basis. nSaver is able to identify apps that are particularly demanding and give you the option to throttle them.