Original Link: http://www.anandtech.com/show/7231/the-nexus-7-2013-review



Truth be told, Google has made (or at least directed the making of) some of the best tablets on the market today. The original Nexus 7 was groundbreaking in that it offered a totally usable platform, married to the latest version of Android, for $199. The Nexus 10 gave us a very quick, ultra high resolution 10-inch tablet for $100 less than the flagship iPad (and with more storage). Both were easily recommendable due to their value, but this year Google is stepping out of the shadow of value and into one of excellence. It starts with the new Nexus 7.

Based on the success of the original Nexus 7, Google went back to ASUS for the second version. In the 12 months since the release of the Nexus 7, the world has changed quite a bit. Expectations for value tablets had been reset by the original Nexus 7 as well as Amazon's lineup of Kindle Fires. Simply showing up with another good value likely wouldn't do anything to further the brand (or market). I get the distinct impression that Google isn't big on not changing the world.

Nexus 7 Tablet Specification Comparison
  ASUS Nexus 7 (2012) ASUS Nexus 7 (2013)
Dimensions 198.5 x 120 x 10.45mm 200 x 114 x 8.65mm
Chassis Plastic + Rubber back Plastic + Soft Touch back
Display 7-inch 1280x800 IPS 7.02-inch 1920x1200 IPS
Weight 340 g 290 grams (WiFi), 299 grams (LTE)
Processor 1.3 GHz NVIDIA Tegra 3 (T30L - 4 x Cortex A9) 1.5 GHz Qualcomm Snapdragon S4 Pro (APQ8064-1AA)
Memory 1 GB 2 GB DDR3L
Storage 8 GB / 16 GB 16 GB / 32 GB
Battery 16 Whr 15.01 Whr
WiFi/Connectivity 802.11b/g/n, BT, NFC 802.11a/b/g/n, BT 4.0, NFC
Camera 1.2MP Front Facing 5.0 MP Rear Facing w/AF
1.2MP Front Facing
Wireless Charging Yes (Qi Compatible)
Pricing $199/$249 $229/$269 (WiFi 16/32 GB)
$349 (LTE)

The result is the new Nexus 7. Identical only in name, manufacturer and screen size, the 2013 Nexus 7 is a downright Apple way to rev a product. Google made it thinner, lighter, faster and better in almost every way.


2013 Nexus 7 (left) vs. 2012 Nexus 7 (right)

The original Nexus 7 was rather thick but it got away with it since the overall footprint of the tablet was so small. The new Nexus 7 truly feels like a slate. It's the type of thing I expect to see carried around on the Enterprise.

I don't miss the rubber imitation leather from the original Nexus 7, it's replaced by a soft touch plastic back. You definitely don't get the premium aluminum feel of the iPad mini, but the device doesn't feel cheap either. The new Nexus 7 is still nice enough that I'm nervous about scratching or scuffing the back.

Both ASUS and Nexus logos are prominently featured on the back. ASUS continues to amaze me by just how far it's come as a company, and the new Nexus 7 is hands down its most impressive tablet creation yet. From a build quality standpoint I really have no complaints about the Nexus 7. While the MeMO Pad HD7 has some creaks and flex in the chassis, the new Nexus 7 feels like a solid slab of soft plastic and glass. It's nice.

Unlike the original Nexus 7, the new model features stereo speakers on back of the tablet. It's an easy feature to take for granted but going back to the old mono design sounds worse.

I agree with Brian that the power/lock and volume buttons are the only real sore spot on the physical execution. They aren't particularly well defined and feel a bit mushy. Even writing this paragraph feels like I'm nit picking though, the build here is really good.

The only other complaint I'd levy against the new Nexus 7 is that the design doesn't particularly stand out as being unique. The iPad has its aluminum, the Moto X has its wood, but the Nexus 7 falls victim to the fact that ultimately it's tough to make these ultra mobile devices stand out. You need a large glass surface and you need a back. Black also tends to be one of the easier colors to sell (get too creative and you end up with inventory problems). It's not a huge deal to me personally, but as mobile devices can often be fashion statements I don't know that the new Nexus 7 has all that much curb appeal.

The Display

What the Nexus 7 lacks in pizazz, it completely makes up for once you power on the display. The 7-inch 1920 x 1200 display produces colors that are not only vibrant but, for the first time ever in a Nexus device, accurate as well. Google really worked on color accuracy this time, with a two step calibration process - once at a high level by the panel maker and once again per device during final manufacturing. The result is just awesome:

The Nexus 7 display is not only visually appealing but stacks up incredibly well in our CalMAN display tests. Although it loses to the iPad 4, the Nexus 7 gets indiscernibly close in many cases and blows the non-Retina iPad mini out of the water. I won't even bother comparing it to everything else in the Android space, they don't hold a candle to it.

CalMAN Display - White Point

CalMAN Display - Grayscale

CalMAN Display - Gamut

CalMAN Display - Saturations

CalMAN Display - Gretag Macbeth

The new panel is also incredibly bright. I typically view 500 nits as the threshold for outdoor usability, and the new Nexus 7 definitely exceeds that threshold. The tablet will drink away all of your battery life if you leave it at this brightness setting indefinitely, but if you need to actually use your tablet outdoors for a while the Nexus 7 works.

Display Brightness - White Level

Display Brightness - Black Level

Black levels are a bit higher than on the original Nexus 7, but the resulting peak contrast ratio is still excellent:

Display Contrast Ratio

Pixel Density Comparison

Pixel density shoots through the roof with the new Nexus 7 display as well. Brian was quick to point out that a major advantage of the Android platform is in its flexible resolution handling. The 1920 x 1200 panel presents itself as a 960 x 600 panel to web pages in Chrome, while other apps can use every last pixel for unique content (e.g. games).

The beauty of not having to double the original Nexus 7's resolution but instead settling on an in-between option like 1920 x 1200 is that Google could get away with a performance mainstream SoC instead of something ridiculously high-end.

The display looks great when viewing everything from photos and movies to web pages and eBooks. My only complaint about the Nexus 7's display is its size. A 7-inch tablet is almost pocketable (in fact I did carry it around in my pocket for a day), but the screen can feel a little cramped.



Platform Power & Battery Life

The new Nexus 7 moves to a slightly smaller battery compared to its predecessor (15Wh vs. 16Wh). The result however is anything but a reduction in battery life. ASUS and Google worked hard to reduce platform power consumption as much as possible. I instrumented both Nexus 7s and measured total platform power, excluding display, to look at the impact of the silicon platform (SoC, PMIC, DRAM, eMMC, WiFi, etc...). The results are beyond impressive:

Idle power is cut in half compared to last year's model. This is by far the most important improvement as most mobile usage models tend to have long periods of idle time. We'll see these power gains reflected in our web browsing test which does have significant periods of simulated reading time between web page loads. The power reduction while running Kraken grows to just over 20%, and even while running Geekbench 3 we see a 16% drop with the new Nexus 7. Only our offscreen 3D test manages to draw more power on the new Nexus 7 than the old one, and that isn't taking into account the nearly 5x increase in performance on the new Nexus. In fact, as impressive as these numbers are - they are even more impressive when you take into account performance. To make a long story short, don't worry about the ~7% decrease in battery capacity as there are enough improvements in platform power and performance (and thus perf per watt) to more than make up for the smaller battery.

We'll start out with our WiFi web browsing test. Like all of our battery life benchmarks we run this test with all devices calibrated to 200 nits and connected to 5GHz 802.11 WiFi (if supported). The test itself cycles through a bunch of desktop websites at a very aggressive frequency. Our test ensures that both the CPU cores and wireless stack can reach their deep sleep states during simulated reading periods. The test continues until the battery is depleted.

Web Browsing Battery Life (WiFi)

The new Nexus 7 does better here than any other small tablet we've ever tested. Remember that 50% decrease in idle platform power? That's exactly why we're seeing a 35% improvement in battery life compared to the original Nexus 7.

Our video playback test involves looping the playback of a 4Mbps 720p High Profile H.264 transcode of the last Harry Potter Blu-ray. All displays are calibrated to 200 nits.

Video Playback Battery Life (720p, 4Mbps HP H.264)

Video decode blocks are fairly well optimized to begin with, so there's not a ton of room for improvement here compared to last year's Nexus 7. Despite the ~7% shrink in battery capacity, the new model manages a 10% increase in battery life though. We also have the first small Android tablet capable of beating the iPad mini in a video playback test here - job well done ASUS/Google.

Our final test involves looping the Egypt HD benchmark until the battery is completely drained. Frame rates are capped to 30 fps to somewhat simulate actual gameplay and not penalize faster GPUs.

3D Battery Life - GLBenchmark 2.5.1

The new Nexus 7 manages to deliver slightly better battery life here despite driving higher frame rates and more pixels. Overall performance here isn't anything super impressive, the only average showing from the Nexus 7.

Google ships the Nexus 7 with an ASUS branded 7W charger, identical to the one you'd find in the box of a MeMO Pad HD7. Given identical chargers and battery capacities, there's no surprise the new Nexus 7 takes the same amount of time to charge as the MeMO Pad HD7 (~3.5 hours).

Charge Time in Hours

The new Nexus 7 also supports wireless charging by implementing the Qi standard. Charge time is a bit slower wirelessly as Qi can only charge at up to 5W. Brian tested Qi functionality in his mini review of the Nexus 7 and didn't have any issues.



CPU Performance

The while the original Nexus 7 was fast for the money, the new Nexus 7 is just fast. Moving away from NVIDIA to Qualcomm, ASUS and Google settled on the APQ8064 Pro. Although we originally assumed this would be a quad-core Krait 200 based SoC, Brian's teardown revealed the part number 8064-1AA. What's special about that part number is it implies newer Krait 300 cores, making the SoC effectively a Snapdragon 600.

The CPU cores can run at up to 1.5GHz, putting it a bit lower than what we've seen from Snapdragon 600 based phones (e.g. HTC One tops out at 1.7GHz, while the US SGS4 hits 1.9GHz).

I was curious as to the impact of the lower frequency when combined with the potentially higher chassis TDP so I compared the Nexus 7 to the US Galaxy S 4. I turned to Geekbench because it offers a nicely woven mixture of single and multithreaded benchmarks, letting me look at peak available single core performance as well as what happens when multiple cores are active and working.

In this first graph we're looking at the first Krait 300 core running the workload. I've zoomed in to a small portion of the benchmark so we can get a better idea of CPU behavior:

The Nexus 7's CPU0 is almost always pegged at 1.5GHz whereas we see a lot of bursty thermal management on the smaller SGS4. This isn't unexpected, but what ends up happening is the sustained performance advantage drops from a peak theoretical max of 26% down to a more reasonable average gain of ~8%.

I was curious to see if multithreaded workloads showed any different behavior. Here we're looking at the fourth CPU core (CPU3). Note that it's not always active, which is why you see parts of the graph drop down to 0KHz. Once again we see similarly static behavior from the Nexus 7. Even with all four cores active, when you need the performance the Nexus 7 delivers a full 1.5GHz. These tests are short enough where we don't see tremendous swings in frequency, but once again we do see some frequency modulation in a smaller chassis.

The end result is that the Nexus 7's 1.5GHz Krait 300 cores are slower than what you'd get in a Galaxy S 4, however the gap isn't nearly as large as you'd expect it to be thanks to the larger chassis and how the platform is tuned. The Nexus 7 can run at 1.5GHz more consistently than Snapdragon 600 based phones can run at 1.7/1.9GHz.

Google Octane v1

Mozilla Kraken Benchmark (Stock Browser)

SunSpider 1.0 Benchmark

The GPU

Qualcomm seems to be frequency binning here, which is standard industry practice. Using binning to create these different SKUs gives Qualcomm pricing flexibility and also gives it the option to give large customers special treatment.

On the graphics side Qualcomm's Adreno 320 GPU makes an appearance. Clock speeds are also limited to 400MHz, compared to 450MHz for the high-end Snapdragon 600 implementations we've seen.

The APQ8064-1AA's dual-channel memory controller is populated with four x 16-bit DDR3L-1600 memory devices, giving the Nexus 7 a healthy amount of memory bandwidth. Peak memory bandwidth available to the APQ8064-1AA is 12.8GB/s, equalling what's available to Apple's A5X in the 3rd generation iPad with Retina display. Tons of memory bandwidth is obviously a pre-requisite for driving a high resolution display, and the combination of DDR3L-1600 and the Adreno 320 GPU delivers a butter smooth UI in all well written Android apps.

Although CPU performance is somewhat middle of the road compared to the rest of the landscape, GPU performance is faster than any other Nexus device on the market - and pretty much faster than any other similarly sized tablet:

3DMark - Ice Storm

3DMark - Graphics Score

3DMark - Physics Score

Basemark X (Offscreen 1080p)

Basemark X (Onscreen)

GLBenchmark 2.7 - T-Rex HD (Onscreen)

GLBenchmark 2.7 - T-Rex HD (Offscreen)

GLBenchmark 2.5 - Egypt HD (Onscreen)

GLBenchmark 2.5 - Egypt HD (Offscreen)

I played Modern Combat 4 as well as Shadowgun, both demanding 3D titles, on the new Nexus 7. Both titles appeared to render at the Nexus 7's native 1920 x 1200 resolution, and both appeared to do so at around 30 fps.



eMMC and FSTRIM

The new Nexus 7 obviously ships with the latest version of Android (4.3), which happens to add a major feature for keeping storage performance high: fstrim. Modern smartphones and tablets fundamentally use a very similar storage architecture to what we see in modern SSDs (solid state drives) in PCs. Instead of a drive featuring a discrete controller, DRAM and NAND flash, these ultra mobile devices typically feature one or two NAND devices with an integrated controller - typically eMMC. To keep costs (and power consumption) low there's also no DRAM cache, which definitely harms performance.

Since the underlying architectures are quite similar, the pitfalls are the same as well. The biggest issue? Performance when operating in a full or near-full state. With tons of files on your internal storage, the data structures that have to track all of those files and where they're located in NAND space get pretty complex, and traversing those structures takes a considerable amount of time. The part that many seem to forget is that once you delete a file in Android, it's not immediately removed from internal storage. The space is freed up in the OS, but the eMMC controller still tracks all of the data as valid bits. It's only when that data is overwritten that the controller knows the previous data didn't matter.

In other words, it's possible to have tons of free space on your internal storage, but have the drive appear full to the eMMC controller (and thus enjoy all of the terrible performance that goes along with it). To make matters worse, you never even have to fill your drive to get it into this state. In order to maintain even wear across all NAND cells (to extend the lifespan of the NAND flash), the eMMC controller will write to new/empty blocks in NAND as much as possible. Let's say you have 10GB of storage and Android writes 1GB of data to new addresses every month and deletes the previous 1GB each time. As long as the addresses being written to never overlap, your drive will be full in 10 months (from the eMMC controller's perspective) but Android will still report 9GB of free space.

fstrim establishes communication between the OS and the eMMC controller to address this problem - and it's enabled in Android 4.3.

Unlike TRIM on standard SSDs, FS_TRIM works more like the manual/scheduled TRIM tools from the early days of consumer SSDs. From Brian's original Android 4.3/TRIM article:

The Android framework will send out a “start idle maintenance window” event that the MountService listens for, and then invokes vold to fstrim filesystems when a few conditions have been met – the device hasn’t been touched for over an hour, no idle maintenance window event has been sent in 24 hours, and the device is either off-charger with 80% battery or on-charger with 30% battery. The goal is to have fstrim run roughly once every 24 hours if you’re in the habit of plugging the device in to charge every night.

Personally I feel like the rules are a bit excessive and I'd love to see us get to active TRIM on these devices, but I guess it's a bit too early for that. Basically if your device has enough charge and you're not using it, Android 4.3 will issue an fstrim command to the eMMC controller. The command passes along a list of all unallocated addresses in the filesystem, which the eMMC controller can then use to purge its logical to physical mapping table/list/datastructure. The process should complete relatively quickly as no new data has to be written, the controller just needs to do some cleanup of internal structures and add a bunch of addresses to the unused block pool. Keep in mind that this simply addresses the issue of your storage getting slower over time. fstrim does nothing to keep performance high if you actually fill your storage to capacity. Given how bad these eMMC solutions are, my recommendation is to try and keep at least 20% of your internal storage unused/as free space.

To showcase just how bad things can get I actually dusted off last year's Nexus 7 and treated it like an SSD. I first filled the device with sequential data, leaving only 300MB free. I then performed back to back random writes across the remaining free space and the performance reduction:

Nexus 7 (2012) Storage Performance
  Sequential Read Sequential Write Random Read Random Write
New After Factory Reset 25.18 MB/s 10.63 MB/s 7.08 MB/s 0.45 MB/s
1st Run After Fill 22.25 MB/s 1.21 MB/s 7.62 MB/s 0.14 MB/s
2nd Run After Fill 26.00 MB/s 1.97 MB/s 7.8 MB/s 0.11 MB/s
3rd Run After Fill 24.57 MB/s 3.18 MB/s 7.96 MB/s 0.16 MB/s
After ~24 hours Idle Time 27.03 MB/s 11.21 MB/s 7.65 MB/s 0.46 MB/s

The columns to pay the most attention to are the write columns (read performance shouldn't change over time). Note that sequential write speed drops by almost an order of magnitude. This incredible drop in performance manifests itself as pauses or stutters. Even when you're just performing simple tasks on your tablet, there are usually tons of background operations going on (e.g. updating system logs). If you look at random write performance here, we see performance drop down to 0.11MB/s - or roughly 27 IO operations per second. If you have more than that amount of IO coming in at the same time, what you'll get are long pauses while the eMMC controller works through its IO queue. Although I didn't include it in the table above, I spent a full day torturing the eMMC on this Nexus 7 and managed to get random write performance as low as 0.02MB/s or 5 IOPS. Sequential write performance in that case was 0.81MB/s, equally disheartening. My point here is that worst case storage performance can get very bad, but looking at the last line of the table you see the incredible impact fstrim has on restoring performance.

I/fstrim ( 118): Starting fstrim work...
I/fstrim ( 118): Invoking FITRIM ioctl on /cache
I/fstrim ( 118): Trimmed 445079552 bytes on /cache
I/fstrim ( 118): Invoking FITRIM ioctl on /data
I/fstrim ( 118): Trimmed 13637656576 bytes on /data
I/fstrim ( 118): Finished fstrim work.

Anyone who had issues with their Nexus 7 slowing down over time will want to upgrade to Android 4.3. Those users considering upgrading to the new Nexus 7 should be fine thanks to fstrim. The only situation where you should see tremendous decrease in storage performance, resulting in IO latency enduced pausing/stuttering is if you physically fill the internal storage close to capacity. Again - my recommendation here is to try and leave at least 20% of your internal storage free. Note that this recommendation applies across Android and iOS.

With all of that out of the way, how does the eMMC solution in the new Nexus 7 stack up? Sequential read performance continues to be quite good for such a small/lower power device. Sequential write speed isn't terrible either. Even random read performance looks solid. It's random write performance that just needs work across the industry. We realistically need to probably be at 10x where we are today in random write performance, perhaps a bit lower if the storage makers can focus on IO consistency/minimum sustained IOPS.

Storage solutions in these tablets are often sourced from multiple vendors, and we can see dramatic differences in performance between them. Brian's review sample was a 32GB model, while the tablet I reviewed had 16GB. The two solutions performed pretty similarly, although my 16GB model did have appreciably better random write performance. Ultimately if you need the space, the 32GB model will be the better performer (you're better off using 45% of a 32GB model than 90% of a 16GB model).

Storage Performance - 256KB Sequential Reads

Storage Performance - 256KB Sequential Writes

Storage Performance - 4KB Random Reads

Storage Performance - 4KB Random Writes

 



WiFi, GPS

I won't spend too much time on either of these points as Brian already did so in his initial review. WiFi duties are handled by Qualcomm's WCN3660 WiFi combo chip. The new Nexus 7 sees an update to include 5GHz 802.11n support, which is a very welcome addition. There's no 802.11ac, understandably for cost reasons. 802.11ac is probably the only thing missing from this otherwise awesome platform.

iPerf WiFi Performance - 5GHz 802.11n

When it comes to GPS, there's good news and bad news. The good news is that Qualcomm's GNSS implementation remains the fastest we've tested as far as time to lock is concerned. The bad news is there seems to be an issue with the Nexus 7's impementation, likely in software, that results in the tablet randomly losing GPS lock. Update: It looks like this has been fixed!

Note that neither my Nexus 7 nor Brian's have exhibited the instability or consistent reboots that I've seen reports of. I had a single unexpected reboot during my GPS testing but that was it. Brian's sample has been running with over 22 days of constant uptime at this point. I also haven't seen any multitouch issues on my Nexus 7, although touch controllers are sometimes sourced from multiple vendors which could explain some of the issues others are seeing. Update: Looks like this one is fixed too!

Camera

The new Nexus 7 adds a 5MP rear facing camera, something its predecessor didn't have at all. While I rarely use my tablet for taking photos, I will admit the absence of a rear facing camera on the old Nexus 7 caught me off guard. Image quality out of the rear camera is decent. I threw together a gallery comparing the Nexus 7's rear camera to the iPad mini, MeMO Pad HD7 and Galaxy Tab 3 8.0:

In well lit situations and if you're sharing photos at lower resolutions, the Nexus 7's camera isn't bad at all. It's not the best thing in the world but in a pinch it's fine. I also threw in iPhone 5 samples as a reference in the gallery above.

Video on the Nexus 7 (2013) is 1080p30 at 12 Mbps, H.264 Baseline with 1 reference frame, and 96 kbps 48 KHz single channel AAC audio.



Final Words

I really like the Nexus 7. It’s easily the best small Android tablet I’ve ever used. The build quality is great, the display is amazing and the hardware is fast. The new Nexus 7 also happens to be the most color accurate Android device we've ever tested - easily competitive with the iPad's Retina Display, and delivers the longest battery life we've ever seen from an Android tablet. You also get the benefits of owning a Nexus device: timely updates and unadulterated Android. My only real complaint about the Nexus 7 is that its screen feels cramped. If you’ve got a large smartphone, the jump between it and the 7-inch display may not be big enough. On the flip side, the 7-inch form factor does make the Nexus 7 quite portable. If you’re ok with the tradeoff, then I have no qualms recommending the Nexus 7 over other 8-inch tablets. 

I typically find myself at odds with what a manufacturer wants to charge for a product, but in the case of the Nexus 7 that’s not true at all. At $229 the base 16GB model is extremely well priced. The adder for the 32GB model is a somewhat reasonable $40. If your Nexus 7 is going to be more of a mobile workhorse, you’ll eventually be able to get a LTE model for $349.

The original Nexus 7 gave us a decent Android experience at a very low cost. This year ASUS and Google raised the bar for sure. The new Nexus 7 is no longer just a decent tablet at a good price, it's an incredible tablet. With this Nexus, it's clear that Google no longer wants to rely on value alone. The 2013 Nexus 7 redefines what you should expect to pay for a truly great tablet. If you're in the market for an ultra portable tablet, and definitely if you're shopping for an Android tablet in particular, the new Nexus 7 should be at the top of your list. It's so good that I'm giving it our Silver Award.

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