ASUS Zenbook UX21E Review

Posted on 20 November 2011, Last updated on 08 March 2020 by

‘HDR mobile computing’ is how I would neatly define the Ultrabook category. These surprisingly powerful laptops can work as efficiently as a netbook and then when you need the power, kick-in cores, turbo and other special features to give you a truly all-round solution that includes video editing, gaming and care-free desktop-style working. The Asus UX21 is one of the lightest, smallest and yet, most powerful of the Ultrabooks, at least in the Core i7 1.8Ghz version we have here. We’re impressed with what’s inside and with its weight and style but there are a couple of potential showstoppers for some people. Read-on to find out more in our detailed multimedia review of the ASUS Zenbook UX21E. Thanks ASUS Germany for the review sample.


The First 5 Minutes

Of all the 2011 Ultrabooks, the ASUS UX21 and UX31 are going to be the most impressive unboxing experiences. Open the quality packaging and you’ll smile. This Ultrabook looks stunning, small and feels strong and sturdy. It’s got a clean finish on the top and bottom and even the Intel and Windows 7 stickers are in a cool grey shading. First boot should be swift (our model was pre-booted with Windows 7 and brought us into Windows 7 in 19 seconds) and welcoming with a healthy welcome sound through the built-in speakers. The screen is bright and the keypad and touchpad feel like high-quality items.  The only thing you might be surprised about is the density of the UX21. The weight is fine but to the eyes it looks like it should feel a little lighter than it is due to its size. Next to a netbook it takes up a similar table area but it’s thin like no netbook that exists. The first 5 minutes is going to really make you feel good about your purchase and that’s what unboxing is all about. I think there’s a marketing term for this experience and whatever it is, ASUS got it right.

In the box you’ll find 2 port adaptors and 2 cases. One for the adaptors, one for the UX21. There’s a ‘wall blister’ lightweight 100-240v AC adaptor with long cable and removable tip included.


Live Review

As part of our review we spent 2 hours with the device while live with an audience. All the videos from the live review are available here along with a round-up of what we found out in the live session. All of it should be included in this review but just in case, take a wander over to the ASUS UX21 Live Review post.


Although we’re dealing with a n impressive list of Core i7, 4GB RAM, 128GB SSD and 1.1KG weight, it needs to be mentioned that there’s a few trade-offs here. The Core i7 is 1.8Ghz part rather than the 2+GHz part you’ll find in slightly larger laptops and the size and weight means there isn’t a lot of room for battery. Sealed inside is a 35Wh set of cells. Full specifications along with links to news and galleries is available here.

Size comparisons


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Shown above: Lenovo S103T (convertible netbook), Viliv S10 (one of the thinnest convertible netbooks), ExoPC (11.6” tablet on Intel N450 Atom CPU)


Ports and Dongles

Getting a bit more serious with the device you’ll want to know about the ports. This is an area where Ultrabooks struggle with the large ports and slots found on tradiational notebooks. Mini VGA, Micro HDMI, only 2 USB ports (one of which is a sleep-n-charge capable USB3.0 port) and a headset port (with a ‘headphone’ icon – we tested it with a headset and it worked.) You’ll need to buy a micro to HDMI cable if you want to use this on a large screen, a USB SD Card adaptor if you want to use SD cards and you’ll need to think about the adaptor cables that are included with the device.





In general we have no complaints about the screen. With a good brightness, average contrast, wide viewing angles and size-matched resoution, we think it hits the mark for the average user but there’s scope for improvement in vertical viewing angles and contrast. Some might be looking for a matt screen too but you can always put a matt screen cover on a glossy screen; Something you can’t do the other way round. Brightness is excellent and although it’s not a true sunlight capable screen, it’s better than most for outdoor usage. There are easy shortcuts for color modes, brightness and backlight-off – something worth doing if you’re waiting for a video to render or playing back internet radio streams, for example. The resolution, at 1366×768 is perfect for easy-reading of default font sizes on Windows 7 at this 11.6” size and the minimum required for Windows 8 Metro user interface apps (next year.)

Keyboard / Trackpad

There’s a lot of talk about the UX-series keyboard and trackpad. Some have reported issues with both, others are 100% happy with the quality. We’re not so positive about the quality of the two items and here’s why.

The trackpad has integrated buttons for those used to the physical movement of mouse buttons but there’s no delimiter between the buttons and the pad so if your finger wanders up into the mouse control area, you affect the mouse pointer, obviously. With double-tap to click, this problem goes away. There’s a second issue we saw with two cases of touchpad lock-up. One of which required a reboot to fix. The other needed some patience before the mouse section of the trackpad came back to life. We’re running Firmware from Sentelic and we’ve just upgrade to to see if it fixes the lock-up issue. As the UX21 goes back to ASUS tomorrow, we’re not likely to have a conclusion on that lock-up solution.

The keyboard may have more significant issues than the trackpad for many.

We found a need to slightly change our typing style to one that requires more concentration than normal. [The author obviously uses a keyboard a lot and is a near touch-typist.] Despite that, we’re still having issues with missed keys because it’s possible to feel the key press action without registering a keypress. It leads you into thinking you don’t need as much pressure when in fact, you have to press beyond the initial ‘give’ of the keypress. We feel it’s a real issue for those that want to use the UX21 for extended typing and as it’s a mechanical issue, only the user can provide the solution by changing their typing style.  [It’s possible that ASUS change their keyboard in future production runs – ideally you’ll check this out for yourself before buying.]

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Apart from the keypress issue, we found the layout good, the integrated indicators on the power (top-right key) , WiFi and shift-lock very useful.

General Performance

The UX21E provides a very wide range of operating modes and scenarios. In battery saving mode (800Mhz) it feels like a very fast netbook and with the SSD providing fast data access and write, it still has the advantage of very quick startup times for large programs. In this mode you’ll get your normal office-based work done without any fuss, major noise and without the CPU or GPU using too much battery. Sunspider results in this mode (a relative indicator of some CPU performance) was 1012ms.

In Quiet Office mode you’ll see the CPU max-out at about 1.2Ghz. It speeds up response for web-pages, unzipping and other common scenarios to the point where you probably won’t notice any speed restriction in most scenarios.

Entertainment mode allows the graphics to run freely with a little cap on the CPU and Performance mode gives you almost everything possible from the device including Turbo Boost to 2.8Ghz where possible.

At the top end, the UX21 not only provides good CPU power through Turbo but it holds it well via powerful cooling. Things get noisy and warm but in gaming and video rendering we’ve seen 2.2Ghz being held for long periods. A lesser cooling system may not provide this level of Turbo Boost capability.


Boot, Standby

You can expect the Asus UX21 to boot in about 20 seconds, even with a big suite of software installed. More importantly, you can rely on standby to keep the device ready for action within 2 seconds of opening the lid. Apart from forced reboots, we haven’t used the power button.

There’s not much more to say about this apart from that it changes the way you use a notebook for quick-use scenarios like Wikepedia look-ups, TV, transport schedules look-up and social networking. Going back to a normal notebook boot sequence (and hard drive) is difficult.


Disk – Speed, size

We can give you detail on the 128GB SSD here by simply saying WOW! This is a fast SSD coupled with a fast controller and fast interface. Not only are the sequential read and write speed impressive but the small-block random read and writes are good too. The performance doesn’t drop off too much in battery-saving mode either.


CrystalDisk High Power MainsCrystalDisk Battery Saving Battery

On the left, performance mode under mains power, on the right are the battery power-saving results.

Making a copy of a anything up to 1GB in size is so fast that you don’t get a chance to really see the progress bar.  In practice it means that application start-up times will be as good as any high-power notebook or desktop. Starting up the latest version of Cyberlink Power Director, a relatively heavyweight program, takes just 5 seconds. Windows Media Center starts nearly instantly.

We would have liked to see a hard-disk activity light but maybe that’s the techie in us just wanting to see when Windows 7 has calmed down after booting .


Like the keyboard, the audio system has had some criticism with some complaints about mains hum on the analogue audio output. In this case we can’t find any trace of a problem here on this [EU, 220v 50hz] system. The analogue audio output is free of any noise, hum or mouse-movement interference and has great stereo separation. The built-in speakers are loud and impressive, if not full-range. Due to their positioning, they have great wide separation to them. 2-channel Digital audio output via the HDMI output was picked up and decoded without problem by our monitor. We were unable to test DTS/AC3 pass-through decoding in the time we had with the Asus UX21. Audio is provided by a Realtek unit with port sensing. The UX21 is not Wi-Di (or Wireless Audio) capable through its Atheros AR9485WG-EG adaptor. For that, you need an Intel Centrino Wifi card.


The video playback capabilities of PCs have three limiting factors. CPU, video decoding hardware and software codecs. Windows 7 provides a good set of software codecs out of the box and supports most hardware video decoders. MPEG2, MPGEG4 part 2 (like Xvid, Divx) and MPEG 4 part 10 (like H.264) along with WMV of course. You’ll need to download and install codecs for other types of file.

The ASUS UX21 supports full HD (1080p) decoding in hardware and we tested it up to 30Mbps which is as high as you’ll get on most consumer video cameras. DVD and BlueRay should be no problem (Blu-Ray not tested) and you’ll find that the CPU barely moves during the process as all the work is done in dedicated silicon. For the 30Mbps H.264 file (2-channel audio) we saw 12% max CPU load.

With the good quality speakers it’s a pleasure to show family videos either on-screen or via the HDMI cable. It’s a shame there’s no Wireless Display support. As mentioned above, this requires an Intel Centrino wireless card.

The Sandy-Bridge 2nd generation core platform used in all 2011 Ultrabooks includes the Intel Quick Sync Video hardware that, through use of an Intel SDK, can provide accelerated encoding capabilities for common video file formats. It’s useful for a number of scenarios but the one that most people will probably use is format conversion so that large-format videos can be reduced to more portable versions. Using Cyberling MediaEspresso, a program that supports the Intel Quick Sync Video subsystem, we were able to convert a 50 second video from 1080p to a YouTube upload-friendly 480p in just 15 seconds –  a 3x real-time conversion rate. For field reporters needing to record in full quality this provides a great way to crunch the video for upload either in quick time (newsrooms will be particularly interested in this) or over low-bandwidth connections, this is an important feature.

1080p video convert

The Intel Quick-Sync video feature found on all Ultrabooks can also be used by video editing programs to speed up, significantly, the rendering process. We’ve used Cyberlink PowerDirector in the past and were pleased with its support of the Quick Sync platform and on the ASUS UX21 it showed even better results on the ASUS UX21 (Core i7)  than on the Samsung Series 3 (Core i3) we tested with it last time.  A quick test of Cyberlink PowerDirector 10 to sequence two 1080p 50 second videos together with a fade and down-convert to a more portable DVD-style 6Mbps format was completed in 24 seconds. That’s 4x real-time. The user interface was quick to use and previews played back without any waiting. Unless you’re doing stabilization, enhancement or other CPU-expensive processes, the ASUS UX21E will provide adequate creative video editing capability for most people, with most types of source video.

Note that the battery drain on rendering is a high 18-20W meaning you’ll only get 1.5-2hrs worth of work out of a full battery on the ASUS UX21. At 4x real-time though, it’s a lot more real rendering than other platforms with much bigger batteries. The cooling on the UX21 is unable to keep the cores cool enough for a long-term use of Intel Turbo Boost in this mode so in subsequent tests, when the device was already warm, the render rate went down quite significantly to 1-2X real time.

There’s a web-cam on the UX21 that only needs a quick highlight as being average. At VGA resolution it doesn’t really fit in with the quality of the rest of the device which is a shame. 720p video conferencing is becoming more and more common. The web cam is flanked by a built-in mic and a video-on warning light, which makes us feel a little more secure!


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There’s clearly many ways to play games on the ASUS UX21E from Flash, HTML5 through to simple native games and on to some more modern high-end games but there’s a long, long distance between what the Ultrabook platform can do and what a ‘gaming rig’ can do. Forget high-end graphics settings on modern, high-end games less than 4 years old but take a look through the back catalogue and you can find some quite impressive experiences, especially if you haven’t played a game for a while.

We start our ASUS UX21 gaming testing with Monster Dash from the Chrome app store. It ran smoothly although these windowed HTML5 games aren’t really the best of experiences. Moving on to the Intel AppUp store we took Pinball HD which played smoothly in full-screen and gave us a good experience. We tested GTR Evolution, a 2008 game, on an external 1080p monitor and it configured itself well to provide a very smooth racing experience at a lower graphics detail level. The experience on the UX21 itself was just as good. Half-Life 2 played surprisingly well under default settings in both battery and mains powered mode with frame rates over 100fps seen after a few minor tweaks. Finally, we did some detailed testing with World of Warcraft under mains and battery settings. Out of the box you can’t expect more than 30 fps in battery or mains-powered mode but with a few tweaks we saw a nice 50fps taking it out of ‘just enough’ territory.

To further demonstrate and detail the gaming capabilities of the UX21 (and Ultrabooks in general – all of the Core i7-based devices should perform very closely to what you see here) we put a video together. High-end gamers will be disappointed but I think many will be surprised just how well the Intel graphics perform.

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Unfortunately we didn’t have time to do LAN tests with the USB adaptor. It provides a 10/100 connection via a USB2.0 connection on either of the USB ports. We also didn’t get time to test the BT4 module although even if we had had time, we don’t have another Bluetooth 4 capable device here to test with.

Wifi was used on a ‘G’ network at 54Mbps. The radio is only 2.4Ghz capable but b,g and n modes are supported. Wifi Direct is not supported as far as we can tell. Wi-Di is definitely not supported. Reception on our local network was above average with 3 bar availability at a two walls / 10m distance but we didn’t make any performance/distance tests. Your local environment may affect Wifi quality.


Performance Testing

Running performance test suites gives you a benchmark with which to roughly compare against other devices.


PCMark7 - mains performance mode

We haven’t tested any other Ultrabooks yet so we don’t have our own comparable benchmarks but if you look around you’ll find the result to be quite impressive. Be aware though that much of it could be a result of the fast SSD.

Cinebench CPU 2 cores battery performanceCinebench CPU 2 cores mains performance


Cinebench OPenGL CPU 2 cores battery performanceCinebench OPenGL CPU 2 cores mains performance


3DMark06 Performance Main3DMark06 Performance Battery


Battery Life

There’s no single battery life figure for a device that can operate in so many different scenarios. The batter drain figures range from 3.9W (the minimum we could get out of screen-off idle) through to over 25W in full-load scenarios but we’ve done a lot of tests, watched a lot of ‘perfmon’ graphs and have come up with the following for you.

  • Internet Radio (battery saving mode, screen off, clean system) – Average 7W drain = 5hrs
  • Web-based work. Wifi-on. Screen-on 40% – Average 8-9W drain = 4-4.5 hours
  • Video playback. Wifi off. Screen on 40%. Video decoded in hardware = 11-13W drain = 3 – 3.5 hours
  • Video rendering using Intel Quick Sync video, performance mode = 20W drain = 1.75 hours
  • Gaming = 20-25W drain = 1.5 – 2 hours

For a Core i7 device at 1.1KG with a very small 35Wh battery in it, these figures are quite impressive.

Heat / Noise

As with battery life, there’s a wide range of operating modes. In general the thermal design is good with both low noise and high cooling extremes. For web-based working the fan stayed off for a totally silent system. Even in charging mode, the base stayed cool. We played back some hardware decoded 720p videos in battery saving mode and streamed a DVD rip with AC3 audio over our local LAN (for 30 mins in our test) and still, the fan stayed off. Obviously audio playback doesn’t tax the system either so it seems ASUS have built quite a nice home theater PC here.

There’s an important note to make about the cooling system though because Intel Turbo Boost relies on good cooling to enable overclocking. Without a good cooling system there’s very little overhead for the use of Turbo boost. Good cooling on a small system can only really be successfully achieved by moving a lot of air. Moving a lot of air makes a lot of noise. The ASUS can get noisy at high workloads but it does a good job and there’s no real fan noise, just the air. Remember we are talking about gaming, video rendering, uncompressing large files and other CPU.GPU heavy operations here and these situations will be rare for many. In our opinion, it’s an advantage to have good cooling allowing Turbo Boost operate for longer. In some situations we saw Turbo Boost settle at 2.2Ghz (the device is a nominal 1.8Ghz remember) in other situations the Turbo Boost dropped away but was back in 5 seconds when the cores were cooler. We saw that in a video rendering operation.

For most operations the UX21 is going to be silent but ASUS seem to have done a great job of cooling where necessary to get the best out of Turbo Boost. For such a tightly built system, we’re impressed. SIlent PC and HTPC fans may want to take a closer look at the UX21 if their requirements aren’t too excesive. Although we haven’t tested it, we expect the larger chassis of the UX31 to have a better thermal characteristic for silent PC usage.

Recovery Mode

ASUS provides an image on a hidden partition which can be used by pressing F9 during boot-up. It’s automated and takes a while as it reboots each time a new drive is loaded. Total time is about 25 minutes. ASUS also provide an application for snapshotting the build and saving to DVD or ISO – a useful application to use once your system is built with the required applications and modifications.


In general use we didn’t experience any stability issues apart from the touchpad lock-up issue but we did experience a serious problem that we think could be a major build fault and we highlighted it to ASUS before we posted this review.

During the live review we experienced two instant shut-downs on removing or inserting the power plug. It doesn’t happen all the time but it happens a lot. Under load, it appears to happen more than under quiet-state but the problem was definitely not a one-off for us. We’ve read about the issue being experienced for others and we feel it’s serious enough to warrant a ‘hold for further information’ before you buy. The ASUS UX21 is the kind of device you can pick up and walk around the house with; close the lid and walk to a meeting with; quickly walk across the room to show someone a funny YouTube video with but if it crashes on removal, or re-insertion of the power, it’s a serious issue. There’s no telling what long-term hard it will have to the filesystem and internal electronics.

The PR agency that sent the review device is sending it back to ASUS for testing. We hope to hear more about this soon.



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Other notes

  • VGA adaptor tested without issues at 1440×900
  • Boot time 21 seconds (with a number of games, applications installed)
  • Resume time – consistently under 2 seconds
  • Only one external monitor can be used at a time. This applies to all 2011 Ultrabooks
  • The headphone port is a headset port
  • No memory upgrade possibility on the UX21

Target Customer

The UX21 with its small profile and light weight is clearly targeted at style-concious hot-deskers. The 35Wh battery doesn’t really make it suitable for road warriors but in commuting or multi-office  scenarios the UX21 would work out as a well-balanced productivity device. In theory the UX21 could be used as a family PC with an attached screen and keyboard although some additional storage may be required in this case. There’s nothing in terms of performance that would disappoint the average user unless they were looking to play the latest games or edit large amounts of home video. Given its ruggedness, it could also make a very impressive PC for students unless all-day battery life would be required. It’s not targeted at price-conscious shoppers, photographers or gamers. Given the keyboard issues, the UX21 is not recommended for those wanting to continuously  input a very large amount of text; That may include some students.


The ASUS Zenbook UX21E (Core i7) proves that serious computing power can be put into a stylish, netbook-class weight. It spans a wide range of usage scenarios including the smooth, carefree experience that’s just not possible on a netbook. HD video viewing, simple HD video editing or conversions and even impressive gaming experiences can be had but in these scenarios the platform works hard, can get warm and noisy, and would drain the battery very quickly. Average battery life and general efficiency is impressive for this weight. If ASUS had produced a sightly higher quality keyboard, the UX21 would have topped the charts for a 1KG professional computing experience but they didn’t and this is something that we would advise all potential customers to test out themselves before commuting to a purchase.  For a phase 1 Ultrabook, it’s impressive and exciting to think what happens in round 2 in mid-late 2012.


You can find a large gallery of ASUS UX21 images in the UX21 gallery hosted over at UMPCPortal. 

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