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Asus Zenbook UX21 Ultrabook, The New Thin
Date: Nov 01, 2011
Author: Dave Altavilla
Introduction and Specifications
We're fortunate enough to get hands-on time with some pretty sexy hardware here at HH and we're not going to make any apologies for using the "s word" as it relates to this hot new notebook from Asus. Though some industry pundits might take issue with us describing this machine as "sexy," you'd have to agree this 12-inch slice of aluminum and cutting-edge technology is pretty damn sleek and pretty.

The Asus Zenbook UX21E is a new ultra-slim notebook by Asus, that fits into the new "Ultrabook" class of machines, to use a term coined by Intel. The Zenbook UX21E is an incredible 3mm thick at the front and 9mm at the rear and has spun metal and hairline aluminum for a strikingly sleek appearance. It's also built with Intel's new low-power Sandy Bridge Core i7 2677M mobile dual-core processor, 4GB of DDR3-1333 memory, a 128GB SATA 3 SSD and an 11.6-inch LCD with a native resolution of 1366x768. 

Here's a quick-take demo of the product in action, but be sure to journey on through the pages ahead for our detailed review with all the analysis and our usual benchmark gauntlet.

Asus Zenbook UX21E-DH71
Specifications & Features
Processor Intel® Core™ i7 2677M Processor
Operating System Genuine Windows® 7 Home Premium 64bit
Chipset Intel® QS67 Express Chipset
Graphics Integrated Intel HD Graphics 3000
Memory 4GB DDR3 1333 MHz DRAM
Display 11.6" 16:9 HD (1366x768) LED Backlight
Storage SATA3 - 128GB SSD
Networking Integrated 802.11 b/g/n
Built-in Bluetooth™ V4.0
Interface 1 x Headphone-out jack (Audio-in Combo)
1 x USB 3.0 port
1 x USB 2.0 port
1 x micro HDMI
1 x Mini VGA
Battery 35 Whrs Polymer Battery
Power Adapter Output: 19 V DC, 2.37 A, 45 W
Dimensions 3mm at the front and 9mm rear - 29.9 x 19.6 x 0.3 ~1.7 cm (WxDxH)
Weight 1.1 kg (2.43 lbs.)
Manufacturer Warranty 2-year limited global hardware warranty, 1-year battery pack warranty
Pricing: $1199 as tested

Intel's QS67 Express chipset offers a power-optimized version of the Sandy Bridge 2nd generation Core mobile platform solutions that have been shipping in the market for some time.  Specifically, the chipset supports things like Intel's RST (Rapid Storage Technology) with SATA 6Gb/s and 3Gb/s support, as well as eSATA (though eSATA is not available on the UX21).  The chipset also doesn't support USB 3.0 technology natively, but Asus offers one port of SS USB 3.0 connectivity via a discrete controller. Other notables with the UX21 are Bluetooth v4.0 for high speed connectivity up to 24Mbit/s with low energy protocol support and the machine's 128GB SSD (other models ship with larger and smaller capacities). This SSD is a 6Gbps "SATA 3" drive, that as you'll see shortly, offers impressive performance.

Asus bundles a nice kit with the UX21E, that includes a nylon and leather carrying case, minimalistic literature pack, a tiny AC adapter that helps you appreciate just how little power this baby draws and a pair of external dongles for wired Gigabit Ethernet and VGA connectivity.
Design and Layout
At first glance, the UX21 has an almost sterile appearance.  Its brushed aluminum exterior could be mistaken for stainless steel.  Upon closer inspection, there are some design queues here that are decidedly Asus and a few that are perhaps embellished upon from others. Apple zealots will immediately point to its Macbook Air like traits but we'd offer those design similarities end at the simple dimensions of the system. In fact, the UX21 measures almost dead-nuts the same as the 11.6-inch MB Air.  It's just a hair deeper and a few ounces heavier. It also has a slightly more solid feel to it in our opinion, though that impression is perhaps subjective.
Image Gallery - Click for high res.

A little research into the specifications of the latest iteration of the 11-inch MacBook Air, shows very similar component configurations as well, including the 128GB SSD, 4GB of DDR3-1333 memory and the native resolution of its backlit LCD, at 1366x768. At the same MSRP of $1199, you also get the 1.8GHz dual-core Core i7, that powers the UX21.  Obviously, there are some extensive similarities here, at least from a specifications standpoint.  The UX21's display is a crisp and vibrant glossy panel that we'd offer has slightly less of a glare issue than the Air as well, perhaps because of its matte bezel.

The UX21's keyboard, layout-wise is almost identical to the Air, though it's clad in aluminum key caps, that we feel are more appealing.  The downside is that the UX21's keyboard is not backlit when required.  This feature would have offered near perfection, if there we just a bit more travel in the key caps when pressed as well. Regardless, a mostly comfortable typing experience is offered by the UX21, with a minimal learning curve.  Its oversized two button trackpad is also reasonably accurate and responsive.  No issues or complaints here for us.

In terms of ports, you get a pair of USB ports, one of the 2.0 and another of the higher speed 3.0 variety.  If you want to connect to a wired Ethernet line, however, you'll need to consume the USB 2.0 port with the included Asus Ethernet adapter, since fitting that functionality along the anorexic edges of the machine was out of the question.  At least you get the option with the UX21, however, along with its VGA output connector too.  These options are not available on Apple's 11-inch sliver notebook. And again, the Asus UX21 offers industry standard USB 3.0 connectivity, over the Thunderbolt IO port on the Air.
Image Gallery - Click for high res.

So the net-net here is, with the UX21 you get a bit more functionality and features, along with the design quality and platform specifications of the competitively priced Macbook Air, but in a Windows machine.  One more small add would have nailed it for the UX21; a simple SD card slot.  Asus' 13-inch Zenbook has one, but it's not available on the 11-inch model.
Software, Multimedia Performance and Experience
Asus does a nice job of bundling some useful apps in with the UX21, while at the same time avoiding excessive bloatware. There are also some helpful widgets pre-loaded on the machine, like a battery level indicator offering a quick glimpse of standby and up-time.  A battery and high performance mode toggle widget is on the desktop as well, which links in with Asus' Power4 Gear Hybrid power management utility for quick, one-click settings. 

Instant On or Really Deep Sleep?
Then there is the "Instant On" switch in the top right of the screen shot above.  This setting is a bit nebulous to us because it actually didn't affect wake from sleep performance much, if at all.  Though the UX21 doesn't support Intel's Rapid Boot technology, Asus did bake some impressive sleep state and recovery technology of their own into the machine.  Asus specifies a 2 second wake from sleep mode, which is pretty impressive to observe in action. Not to mention, the machine will cold boot in about 12 - 15 seconds, thanks to its speedy SSD.  But we digress; if you toggle that Instant On switch, you'll note the Standby time on the gauge widget will increase up to three fold in some cases.  We witnessed a 3 day standby time going to 8+ days when we enabled the instant on setting.  This setting essentially allows a deeper sleep state for the system when it's enabled, and again, we noticed no appreciable change in wake from sleep time.  Regardless, all told, the bonus standby time is a very nice feature indeed.

Asus LifeFrame

Asus also bundles a nice, simple suite of utilities and apps with the UX21, called "Asus Tools." Here you find things like back-up and restore tools, system security apps including facial recognition software for access and logon security, a driver update tool, word processor and Asus "LifeFrame," seen above.  LifeFrame is a webcam software suite for stills, audio, video and various content creation utilities.

1080p H.264 HD Video Playback - Marvel Avengers Trailer - CPU Utilization < 5%

Performance-wise, we're going to jump into the numbers in intimate detail on the pages ahead but here's a quick look at some high level indicators.  The first check is the Windows 7 Experience rating above for the UX21. The weakest link of course would be the graphics subsystem but it's still not too shabby at a rating of 5.5.  However, processor and memory performance is decidedly more impressive. Those indicators noted, also, when's the last time you saw a notebook score a perfect 7.9 for its storage subsystem in WEI? And this is a performance bottleneck area, where you'll notice the system responsiveness that goes along with that score.  It's very tangible and the UX21 always felt as snappy as just about any notebook, desktop replacement or otherwise, that we've tested.

Finally, before we fired up our test suites, we kicked back with a little HD video and the UX21 handled it without breaking a sweat.  Here we're showing Windows Task Manager Performance Monitor running in the foreground, while a 1080p H.264 QuickTime trailer for the awesome-looking upcoming Marvel Avengers movie plays in the background.  You can also see that we have the Intel CPU clock speed widget fired up as well.  Turbo Boost would occasionally scale the dual-core Core i7 up to 2.6GHz (max is 2.9GHz), but CPU utilization never peaked over ~10% and usually oscillated between 2 - 5%.
SiSoft SANDRA, ATTO and Cinebench
We began our testing with SiSoftware's SANDRA 2011, the System ANalyzer, Diagnostic and Reporting Assistant. We ran four of the built-in subsystem tests that partially comprise the SANDRA 2011 suite (CPU Arithmetic, Multimedia, Memory Bandwidth and Physical Disk Performance). All of the scores reported below were taken with the Zenbook running at its default settings with full performance mode enabled and the notebook plugged into the AC adapter.

Synthetic General Performance Mertrics

SANDRA CPU and Memory Performance

SANDRA Multimedia and Physical Disk Performance

SANDRA's numbers show the new Core i7 dual-core CULV chip is faster than a similarly clocked Core i5 in both Integer and FPU metrics.  Memory Bandwidth with the system is a very robust 16.33GB/s on average and the Zenbook offered competitive Sandy Bridge throughput that leaves previous generation Arrandale bandwidth numbers in the rear-view.  Good stuff. 

However, check that bottom right graph, if you look at nothing else here.  This is the physical read performance test from the Zenbook's 128GB ADATA SSD.  It's based on a SandForce 2200 series 6Gbps SATA controller and at 500+MB/s, it's the fastest notebook drive or SSD we've seen in action to date.

A Double-Take at The UX21's SSD Performance with ATTO -
With these kind of read numbers, we had to check the rest of the story in ATTO.  Below are read and write throughput metrics on various transfer sizes.

Once you approach 16 - 32K transfer sizes, raw 500MB/s read-write performance is realized with the Zenbook, peaking at 514MB/s for writes and 555MB/s for reads.  It's no wonder the system felt so responsive and booted so fast.  Glorious bandwidth.  Gotta love it.

Cinebench R11.5 64-bit
3D Rendering Performance

Maxon's Cinebench R11.5 benchmark is based on the company's Cinema 4D software used for 3D content creation and tests both the CPU and GPU in separate benchmark runs. On the CPU side, Cinebench renders a photorealistic 3D scene by tapping into up to 64 processing threads (CPU) to process more than 300,000 total polygons, while the GPU benchmark measures graphics performance by manipulating nearly 1 million polygons and huge amounts of textures.

We'll spend a bit of time analyzing the numbers here because they're interesting. First, let's look at the OpenGL scores. The Zenbook isn't a machine that is designed to handle the workloads of a high-end professional 3D rending tool like Cinema 4D.  However, Intel's graphics drivers have been slowly improving since their Sandy Bridge architecture first launched.  Though it can't compete with the likes of a discrete mobile GPU from NVIDIA or AMD, it actually out-paces the Core i5 2410M, which is slightly stronger from a CPU standpoint in this test, due to its higher base clock speed.  The i5 2410M is also a 35W TDP CPU, versus 17W for the i7 2677M, however. Both chips have 1.2GHz max dynamic graphics core clocks, though the ThinkPad Edge was running previous generation Intel graphics drivers. 

From strictly a CPU performance view, the Zenbook puts up a reasonably solid number, falling in between the i5 2410M and its high base clock and the Core i7 2620M with its 3.4GHz max Turbo Boost speed.

PCMark Vantage and PCMark 7
Futuremark's PCMark 7 is the latest version of the PCMark suite, recently released this spring. It has updated application performance measurements targeted for a Windows 7 environment. Here's what Futuremark says is incorporated in the base PCMark suite and the Entertainment suite, the two modules we have benchmark scores for you here.

Futuremark PCMark 7
General Application and Multimedia Performance
The PCMark test is a collection of workloads that measure system performance during typical desktop usage. This is the most important test since it returns the official PCMark score for the system
  • Windows Defender
  • Importing pictures
  • Gaming

Video Playback and transcoding

  • DirectX 9

Image manipulation
Web browsing and decrypting

The Entertainment test is a collection of workloads that measure system performance in entertainment scenarios using mostly application workloads. Individual tests include recording, viewing, streaming and transcoding TV shows and movies, importing, organizing and browsing new music and several gaming related workloads. If the target system is not capable of running DirectX 10 workloads then those tests are skipped. At the end of the benchmark run the system is given an Entertainment test score.

Futuremark only recently introduced its PCMark 7 suite, the successor to PCMark Vantage. As time goes on, we'll have a bigger sampling of scores to compare systems with, but in the meantime, we've pull together what we have compiled thus far, for you here...

If ever there was a "Poster Child" for the benefits of SSDs, especially in notebook platforms, it would have to be the Zenbook UX21. See that graph up there?  That's a 2.4lb ultralight laying to waste a $4000 desktop replacement notebook.  Though the Alienware M18x would obliterate the Zenbook in a gaming scenario, PCMark 7 is a general purpose computing, business application and multimedia performance test.  Here, the Zenbook UX21's 6Gbps SATA SSD rips through the benchmark like a hot knife through butter.  Its processor isn't waiting around for data requests to be delivered from the storage subsystem in the machine.  It's just punching out workload and leaving lesser-equipped notebooks behind.

The M18x has a standard 7200RPM 750GB hard drive inside.  If you were to drop an SSD into the M18x , since it's also an Intel 6 series chipset machine (Sandy Bridge-based) with SATA 6Gbps support, it would be a different picture.  Nevertheless, this test illustrates just now much of an impact an SSD can have on overall general performance.

Futuremark PCMark Vantage
Simulated General Desktop Performance
Next up, we ran our test systems through Futuremark’s previous generation total-system performance evaluation tool, PCMark Vantage. PCMark Vantage runs through a host of different usage scenarios to simulate different types of workloads including High Definition TV and movie playback and manipulation, gaming, image editing and manipulation, music compression, communications, and productivity.  Since we have a large database of scores for this test, we felt it would be good to give you additional reference points to compare to.

We left the M18x in this comparison chart, just for giggles, so you could draw the same reference point as our PCMark 7 test.  The picture doesn't change much.  Game, set, match - Zenbook.
FarCry 2 and Left 4 Dead 2 - Gaming Performance
Gaming situations aren't going to be a strong suit for the Asus UX21E Zenbook, but that didn't stop us from running a few base-level tests, just to see what the machine had under the hood and if there was any sort of capability for gaming at play here... pun intended we suppose.

Far Cry 2 and Left 4 Dead 2
DirectX 10 Gaming Performance

FarCry 2

Like the original, FarCry 2 is one of the more visually impressive games to be released on the PC to date. Courtesy of the Dunia game engine developed by Ubisoft, FarCry 2's game-play is enhanced by advanced environment physics, destructible terrain, high resolution textures, complex shaders, realistic dynamic lighting, and motion-captured animations. We benchmarked the test systems in this article with the FarCry 2 benchmark tool using one of the built-in demo runs recorded in the "Ranch" map.

FarCry2 drops the UX21 right about in where we expected it.  The higher overall clock speeds of the Core i5-2520M and Core i7-2820QM power it past the other systems with integrated Intel HD 3000 graphics cores.  The Zenbook does manage to edge out the ThinkPad Edge, but either way, frame rates at these settings aren't playable.  You'd have to drop down image quality a bit or resolution, to get acceptable performance.

{Left 4 Dead 2

Left 4 Dead 2, though it has reasonably good visuals, is a bit easier on the graphics subsystem.  This was a game engine that the Asus UX21 Zenbook could handle a bit better.

Here we see playable frame rates, at reasonably good image quality settings, right on up through native resolution of the Zenbook UX21's 11.6-inch screen. 

Battery Life Performance
With an Ultralight class of machine that the Zenbook UX21 has to compete in, battery life is a very important watermark.  After all, if you have to tether back to the wall with your thin slice of techno-coolness too often, what's the point of building such featherweight notebook?  Below are our worst and best-case battery life test results, with Battery Eater Pro. Also, please note that, in the same benchmark chart, we have listed simple web browsing up-times as well.

Battery Life Test
Heavy and Light Workloads

In terms of our standard BatteryEater Pro test, the UX21 offers respectable battery life, on the order of about 3 hours in this worst-case test condition, besting machines like Dell's XPS 15z and the ThinkPad Edge by Lenovo.  However, as indicated by the top gold bar here in the graph, if you're just browsing the web and checking email, you can expect over 4 hours of available computing time.
Conclusion and The Wrap-up
Performance Summary: The Asus UX21E-DH71 surprised us more than once in our assortment of tests. The machine offered some of the best standard application and multimedia performance scores we've seen from an ultralight machine to date. The UX21's PCMark Vantage and PCMark 7 scores exceeded (by a long shot) even some heavy-duty desktop replacement machines, thanks to its ultra-fast SSD. In other areas, the Core i7-2677M and its 4GB DDR3-1333 complement held its own versus similarly equipped machines, though it fell short a bit in more strenuous gaming scenarios, which of course is to be expected in this class of machines that aren't designed or marketed as gaming systems. That said, the UX21 does have some capability under the hood for light-weight DX9/10 gaming at more modest image quality settings.

From one point of view, the Asus Zenbook UX21's closest competitor would be the 11-inch Apple MacBook Air. Looking at specifications and features alone, the UX21 lines up quite nicely versus Apple's offering.  In about the same price range (as our machine was configured), you get additional wired Ethernet connectivity and standard external display output, both of which aren't options for Apple's product. Sure, you can tap into a Thunderbolt-enabled display or storage array with the new MacBook Air, but you can be sure it'll be more expensive. Then again, you're only getting standard VGA output with the UX21, so this could be thought of as a trade-off.  The bottom line is, Asus has delivered a very competitive product in the UX21 versus the latest update to the MacBook Air, and that's a watermark that's difficult to measure up to.

Consider also that you have options with the UX21 series.  You could opt for a UX21E-DH52, which comes equipped with a Core i5-2467M at 1.6GHz and Turbo Boosts to 2.3GHz, for $200 less, or around $1000 total.  Then there is the UX31 series that offers a larger 13.3-inch screen with similar specs to the 13-inch Air.  Either way, Asus delivers a whole lot of style, substance and ultra-portability with their new ultrabook U series line.  While some of us around the HH lab would opt for the larger UX31 Zenbook, others feel the UX21 is ideal.  You really can't go wrong either way though.  We're thoroughly impressed with the Asus UX21 Zenbook.  The "Zen" namesake feels almost fitting, and not just marketing.  In some corny sense you might say that Asus has demonstrated the attainment of "enlightenment" through their years of notebook design experience and the Zenbook UX21 delivers with the wisdom of those years.

  • Gorgeous good looks
  • Exceptional build quality
  • Light as a 2.4lb feather
  • Top-shelf ultra-low power components
  • Solid battery life
  • Great performance
  • No DVI or HDMI output
  • No backlit keyboard
  • Key cap travel is a bit shallow, takes getting use to

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