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True · thinnest, Dell Venue 8 7840 tablet evaluation
Charles Fang 2016-03-16 17:16

When the 6.1mm thick iPad Air2 was released, everyone thought it was the thinnest tablet, but in fact, the title of "thinnest tablet" was taken away by Dell's Venue 8 7840 in September 2014 and has remained so far. But it was not officially launched until January this year. Can Dell continue the legend of Streak 5 this time?


parameter

appearance

The thickness of the machine is 6mm, which is only 0.1mm thinner than the second place iPad Air2 and Sony Xperia Z4 tablet. But normal people without the spiral micrometer hand of Wang Zhang can't tell the difference. However, the size of the Venue 8 7840 is smaller, and the shock of picking it up for the first time will be much stronger.


The back of the body is made of aluminum alloy, and the speaker cover at the bottom of the front is made of plastic. The aluminum alloy makes it feel strong, but there is no chamfer or excessive arc at the edge. With a thickness of 6mm, it feels like a kitchen knife when it is picked up. Fortunately, the weight is only 306g (331g for iPad mini3), so the holding pressure is not large.


For the borderless appearance, the front camera and stereo speakers are placed under the fuselage, which makes its appearance more special. This asymmetric design will not only affect the self timer experience when holding the machine vertically, but also affect the experience of holding the machine horizontally - only one side provides the holding position.


The ultra narrow three side frame (upper and left and right) will also bring some inconvenience in use. The narrow border of the iPad somehow has iOS anti touch optimization (when it detects a large area of finger contact with the screen, it will automatically ignore its impact), but Android has no similar optimization. Usually, if you don't pay attention to the phone, you will press the edge of the screen to cause false touch, and you will often find that you have pressed the screen when you find that the page cannot scroll

In general, it is a machine with good workmanship and design. It is light, thin and strong, and will not be bent casually. The frame is extremely narrow, and the visual impact and force are very high. Unfortunately, the edge of the fuselage is too sharp to hold comfortably, and the ultra narrow frame is not optimized to prevent accidental touch.


performance

Apart from having only 16G storage space, the parameters of the machine have nothing to complain about. However, the tradition of Intel processors with "strong CPU and weak GPU" still makes us worried about their GPU performance.

The CPU of the machine is Atom Z3580, which belongs to the Mooerfield product line. It uses a 4-core Silvermont architecture with a 22nm process, and the maximum dominant frequency is 2.33GHz.

In terms of CPU performance score, the company inherits the excellent tradition of Intel's strong core computing performance, which is reflected in the fact that many flagship companies that use ARM cores do not lose much, and even beat the entire Qualcomm family, just slightly weaker than Apple's A8 and Nvidia's Tegra K1.


However, graphics performance is still the weakness of Intel processors. Compared with the powerful computing performance, its graphics performance is only midstream, and it is still far behind the Nexus 9 at the same price.


However, the actual performance of the machine is surprising. In terms of actual fluency, there is a huge gap between its performance and the running score, and the phenomenon of "stuck" and "frame drop" still appears in the Android high split panel.

The GPU rendering curve is not very good under the desktop. There will be perceptible frame drop and stuttering in the drop-down notice bar, rotating screen, and long list page. After the dynamic desktop is opened, the desktop slides out 60 frames, occasionally hitting 30 frames... But the machine is still using Android 4.4, which should be improved after upgrading 5.0.


GPU (game) performance

The Mooerfield to which the Z3580 belongs is the only Atom series that uses PowerVR GPUs. The PowerVR G6430 GPU it uses is the one on the Apple A7 processor (iPhone 5s).

3DMarks


GFXBench

In terms of GPU performance, although it is the same GPU, there is a big gap between Android devices and iOS devices. What's more sad is that the performance of Android devices is worse, and the resolution of the machine is far higher than that of the iPhone 5s, which leads to its performance being weakened again.

Although the performance of this GPU is not bad, its competitors are too strong: the A8X processor on the iPad Air2 is equipped with an 8-core GPU, and the Tegra K1 with a Kepler architecture GPU is a monster with abnormal GPU performance, and the Nvidia Shield tablet equipped with Tegra K1 is only $299.


NAND flash performance

Although this parameter is rarely mentioned by manufacturers (they generally only talk about capacity), if the flash speed is too slow, it is likely to become a performance bottleneck, especially when heavy reading and writing are required. Many times, we think that the "one card, one card" caused by background rogue processes, background downloads or installations is actually just because the machine's flash memory read and write speed is too slow.

Random read and write


continuously read and write

The average flash memory performance of the Venue 8 7840 is not high, but it will not become a performance bottleneck. However, its 16G capacity will be a bigger problem than its speed.


Screen performance

Compared with mobile phones, tablets actually have higher requirements for screens. After all, we use tablets for their large screens. However, given the performance of Dell's previous mobile devices, we did not have too high expectations for the 8.4 inch 2560x1600 AMOLED screen on the machine.

The maximum brightness in manual mode is 211 nits, which is lower than that of Samsung tablet and motoX with the same AMOLED screen.

However, the lower the proportion of white in the screen (APL), the brightness of the machine will increase, up to 430 nits. In daily web pages and most applications, white occupies about 80% of the area, which means that the maximum brightness of the machine is about 250 nits, but it is still too low.

Moreover, the machine does not have the automatic mode on Note4 and MotoX that can "overclock" the screen brightness, which makes it not very visible in the sun.


The gray scale of the machine is in the middle and lower reaches, and the color temperature is 6203K. Because of the blue "powerless", the machine screen appears red shift, making the white display red.


The more sad thing is still to come. In terms of color saturation, the machine shows serious green oversaturation. If the intensity of green can be displayed as a percentage, its supersaturation degree is: it can change the original 60% green to 100% green


On the red green transition color, the screen saturation is directly high. But our human skin color just falls in the range of transitional color, which will cause serious color deviation when the machine displays human skin color.

In fact, this super high saturation is a good thing for machines with color tuning, but the Venue 8 7840 screen has obviously not been tuned (at least not properly tuned).  

Of course, the screen of the machine is not so bad as that shown by comparing scores. Even at the first glance, the screen will be amazing. The main problem is that it is just too gorgeous, and the visibility in strong light is not strong, but if you are a heavy user of pictures and videos, you are not recommended to choose this machine

Recently, the screens supplied by Samsung have encountered problems of color adjustment and low brightness. In addition, the P row of the machine screen still makes the edge of the text slightly jagged. In fact, the A screen is also good, but the premise is Samsung's own tuning, if not, it is recommended to use the IPS screen


Endurance

With 5900mAh battery, the official announced that the machine has 10 hours of life. In the actual measurement, the machine persisted for 9.5 hours in the web browsing test, slightly losing to the iPad Air2, nearly one minute less than the Nexus 9. In the video playback test, the machine ran for 12.77 hours (there were many dark spots in the film, and the A screen became angry instantly).


In terms of charging, the official standard 5V2A charger takes 2.78 hours to fully charge, which is faster than some mobile phones. It's easy to beat competitors who often take 3-4 hours to recharge. The endurance and charging speed of the machine are quite worthy of praise.


System and application adaptation

In terms of the system, it is basically the native Android 4.4 plus some Dell applications that can be uninstalled. The 16G storage space is 9.12G available from the factory.


Compared with the system, the third-party application is the more sad pain of Android tablet, which is basically the direct stretching of mobile app, which will look more painful on the tablet with non 16:9 screen. The saddest thing is that Google's own Gmail has not done a good job of tablet adaptation... The larger screen has not replaced a single screen with more content, and there are various problems of stretching and deformation of the font.


Of course, there are also things worth praising, such as Hangout and Filpboard.


photograph

Young people may think it is funny to take photos with a tablet, but the aunts who take photos with a tablet in major scenic spots tell us that the older generation needs a larger screen as a viewfinder because of their presbyopia. In addition, the mobile phone screen is too small, so their use probability is small. So for filial piety or the previous generation of fashion, the flat camera is still useful.

The original front camera of the machine is 2.4 million pixels Sony IMX132 (single pixel 1.12 µ m, 1/6.95 inch), aperture f/2.2; The original rear camera is OV8858 (single pixel 1.12 µ m, 1/4 inch), aperture f/2.4.

The photographing interface and functions are relatively simple, but ISO (up to 800), white balance and exposure compensation control are supported.


The photography performance of the machine is not very good. The main problem is noise control. Even in strong light, there are still many noise points. The weak light noise will naturally become more, and the white balance is also unstable. Compared with the iPad air2, which is also an 8 megapixel camera, it is far from perfect. In addition, there are three cameras behind the fuselage when taking photos, so it is difficult not to block them when taking photos


The biggest selling point of the machine camera is the two 720P depth of field cameras above it, which are 8cm apart. As the name implies, they are used to record depth of field information. Officially, it can record the depth of field information within 0.9m to 9.1m, and then refocus and control the depth of field (background virtualization) in the machine's own image library.

The machine can even measure the distance in photos, but there is still a small bug. The actual distance between the two houses in the above figure is 28 feet (8.5 m), and the measurement line above is closer to the truth. However, when the measurement line is placed below a lot of interference, the measurement error is very large.


The background blur is similar to multi camera models such as HTC M8 and Glory 6Plus, but the use experience is not very good.


More worth mentioning is the local filter function, which can identify objects at different distances through the camera, and then you can add a separate filter, which is much faster than PS, and has a good use experience.

However, because the depth of field camera is 16:9, after using the depth of field auxiliary camera, the image of the rear camera will also be cut to 16:9, with some pixel loss.

In general, the performance of the rear camera is not ideal, and the power of the depth of field camera has not been fully utilized. We look forward to the subsequent algorithm improvement.


summary

The Venue 8 7840 is definitely one of the most beautiful Android tablets: the aluminum alloy shell is solid, the ultra narrow frame and the ultra-thin body are very impressive. Although the grip and edge anti mistouch optimization still need to be improved, it is still a tablet with good hardware design.

Its positioning is high-end tablet. Dell has given it a good hardware design and selling points (high split screen, ultra-thin thickness and dual depth of field auxiliary cameras), but its performance and display effect still need to be improved. Moreover, 16G storage space is really a big slot.

At the price of $399, the Nexus 9 has stronger performance and larger screen (but it is a plastic body and not light), while the NVIDIA Shield tablet with the same exaggerated performance is even $100 cheaper. When it comes to systems, the iPad mini3 at the same price and the iPad Air2 that cost $100 have overwhelming advantages.

However, the computing performance of the machine is good, and the new Intel core has good power consumption control ability, and the machine's endurance and charging time are very good. In general, at the price of $399, its appeal is not very strong, but its feel and design are still worthy of praise.

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