The Google Nexus 9 Review
by Joshua Ho & Ryan Smith on February 4, 2015 8:00 AM EST- Posted in
- Tablets
- HTC
- Project Denver
- Android
- Mobile
- NVIDIA
- Nexus 9
- Lollipop
- Android 5.0
Battery Life
It goes without saying that battery life is one of the most important aspects of a mobile device. After all, a mobile device isn’t really mobile if it can only be used for an hour before running out of battery. In order to test this, we turn to our standard suite of battery life tests, which include our web browser battery life test, along with some compute-bound benchmarks to characterize battery life across various use cases.
However, as the Nexus 9 introduces such a unique CPU architecture, I felt that it was necessary to try and adequately capture the full extent of battery life. To this end, I’ve introduced a new test that is really quite simple but important, as we can start to separate display power from everything else since it can often be the single largest consumer of power in a test. In order to do this, everything that could run during a test is disabled, and the device is placed in airplane mode with the display at 200 nits. A white image is displayed on the screen from a full charge until the device shuts down.
Interestingly enough, the display runtime on the Nexus 9 is about as good as it gets when compared to other devices for which we have data. I suspect we’re looking at the direct result of the large battery combined with an efficient display, as the Nexus 9 can last as long as 15 hours in this test compared to the iPad Air 2’s 10 hours.
Unfortunately, the massive lead that we saw with the pure display test is significantly eroded in our web browser test. Our web test is primarily focused upon CPU, connectivity, and display efficiency. Seeing as how the Nexus 9’s display is far ahead of the iPad Air 2 and connectivity should be broadly similar in power efficiency, it seems that all of the efficiency gains from the display have gone into powering the Denver CPUs. It’s likely that process has a significant effect on this, so the more valid comparison is between SHIELD Tablet and the Nexus 9. At any rate, the Nexus 9 does manage to deliver solid battery life performance in this test which is definitely a good thing.
When we move to our pure video test, the Nexus 9 does have a minor regression when compared to the Nexus 7 (2013) and SHIELD Tablet. In this case, the AMOLED displays on the Galaxy Tab S line make for an easy victory due to the relatively high amount of black displayed in the content. The gap is closed between the two devices though, due to a reduced focus on SoC power.
While our web browsing test can give some idea of efficiency, there are often cases where more compute is directly used to support a better experience. To try and test for these compute-bound cases, we use Basemark OS II’s CPU battery life test and GFXBench’s T-Rex rundown for a GPU battery life test. As with the web browsing tests, these are run at 200 nits to keep things relatively equal.
In Basemark OS II, the Nexus 9 does a surprisingly good job as the CPU manages to keep incredibly high sustained performance. The large battery and efficient display seem to help to a significant extent.
In GFXBench, it seems that not much changes overall. The GPU is definitely more power hungry than the PowerVR Series 6XT line-up and sustained performance is noticeably worse, but it’s in line with the SHIELD Tablet. End of run performance ends up a bit lower, but higher than one might expect. This is likely due to differing ambient temperatures. In practice, skin temperatures are about 45C in this test and localized to the top half of the device, and it’s likely that internal temperatures are around 80C as well. Seeing as how Tegra K1 can theoretically draw 33W in platforms such as the Jetson TK1 dev board with active cooling, it's incredibly impressive to see NVIDIA effectively keep such a powerful SoC within the constraints of a passively-cooled tablet.
Charge Time
While battery life is one part of the equation, charge time is an equally important aspect of overall battery life. To measure this, we measure the time from when charging begins to when the device reaches 100% charge. This is confirmed by taking measurements at the power outlet to make sure that power draw is below a certain level.
In this regard, the Nexus 9 is merely average for a tablet, although it does fall behind the competition as it uses a 5V, 1.5A charger for 7.5W instead of the 12-15W chargers that we’ve seen recently. It shouldn’t be a big issue, but in general this does mean that devices like the Galaxy Note 4 are actually better at battery life overall when compared to most tablets.
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seanleeforever - Wednesday, February 4, 2015 - link
2nd that.I am not here to read about how fast the tablet is or how nice it looks. i am here for in depth content about the chip. would it be nice that this content was available since the release of the product? absolutely, but given the resource it would either be a brief review that is going to be the same as review you can find from hundred of other websites, or late but in depth.
honestly i think anand should be targeting at more tech oriented contents that's few but in depth, and leave the quick/dirty review for other websites.
superb job.
WaitingForNehalem - Wednesday, February 4, 2015 - link
Yeah but who cares about tablets??!! I don't come to Anandtech to read about budget tablets, or SFF PCs, or more smartphones. The Denver coverage was not even that in depth TBH, just commentary on the NVidia slides. I have a EE degree and some of the previous write ups were so in depth they could be class material. This one isn't which is fine but I don't think it excuses how late it came out. The enthusiast market is growing and you should be targeting that demographic as you previously have, not catering to the mainstream like hundreds of sites already do.retrospooty - Wednesday, February 4, 2015 - link
The enthusiast market is growing ? What with CPU's not really getting, or needing to be any faster for several years now, and a standard mid range quad core i5 (non-overclocked) being WAY more than powerful enough to run 99.9% of anything out there, how is the enthusiast market is growing? Most enthusiasts I know don't even bother any more... There just isnt a need. Any basic PC is great these days.WaitingForNehalem - Wednesday, February 4, 2015 - link
I totally agree with you. That doesn't change the fact that the market is growing as more users are adopting gaming PCs. Enthusiasts now actually command a sizable portion of desktops sold. Intel's Devil's Canyon was in response to that.retrospooty - Thursday, February 5, 2015 - link
OK, I get what you mean.I guess I am still in a mind set where a PC "enthusiast" is your overclocker, tweaker, buying the latest and fastest of everything to eek out that extra few frames per second.
Today, a mid range quad core i5 from 3 years ago and a decent mid-high range card runs any game quite nicely.
FunBunny2 - Thursday, February 5, 2015 - link
There was a time, readers may be too young to have been there, when there was a Wintel monopoly: M$ needed faster chips to run ever more bloated Windoze and Intel needed a cycle-sink to soak up the increase in cycles that evolving chips provided. Now, we're near (or at?) the limits of single-threaded performance, and still haven't found a way to use multi-processor/core chips in individual applications. There just aren't a) many embarrassingly parallel problems and b) algorithms to turn single-threaded problems into parallel code. I mean, the big deal these days is 4K displays? It looks prettier, to some eyes, but doesn't change the functionality of an application (medical and such excepted, possibly).Does anyone really need an i7 to surf the innterTubes for neater porn?
nico_mach - Friday, February 6, 2015 - link
I think the chip coverage was superb, I don't have an EE degree and I'm pretty sure that's what the website is steered towards. And I still think I got it.It's fascinating the number of layers involved in this Android tablet, and speaks to why Apple can optimize so much better. There's the chip->NVIDIA chip optimizer->executable code->Dalvik compiler/runtime->dalvik code. I mean, when the lags are encountered, that's twice as many suspects to investigate.
I still think that the review is a little harsh on Denver. It's hitting the right performance envelope at the right price. While it's an mildly inefficient design, clearly NVIDIA is pricing it accordingly, and that might be a function of moving some of the optimization work to software. And that's work that Apple and MS do all the time - Apple much more successfully, obviously. There's a real gap in knowledge of how efficient Apple's chips are vs how optimized the software/hardware pairing is.
dakishimesan - Wednesday, February 4, 2015 - link
I have no interest in tablets, but the deep dive on Denver was a fascinating read, and still completely relevant even if the product is a few months old. Thanks for the great review.Sindarin - Wednesday, February 4, 2015 - link
...can I offer you a cup of hot chicken soup laddy? .....maybe some vicks vapor rub? lol! c'mon dude! we're all sick(vaca) in December!hahmed330 - Wednesday, February 4, 2015 - link
Hi, outstanding article with incredible attention to detail... Do you think its possible to run Dynamic Code Optimizer on per say 2 or maybe even 4 small cpu cores dedicated to doing all the software OoOE functions instead of using time slicing? (A53s or just some XYZ narrow cores for a potential 2+2 or 4+4 or maybe even 8+8)Also whats the die size of a denver core in comparison to a enhanced cyclone core?? That is where a lot of gains are possible potentially 30%-50%..