The Asus Zenbook Infinity UX301LA is the successor to the Zenbook Prime UX31A, which we gave five stars a year and a half ago. And with an Intel Core i7-4558U processor, two 128 GB RAID 0 SSDs and an ultra-thin chassis, the stars are lined up for similar performance this year.
The second you open the box, you can tell Asus put a lot of care and attention into the design and aesthetics. The UX301LA sits waiting for you to slide it and its soft cleaning cloth out from the imitation-leather pouch in which they lie, at which point you notice how thin (15.5 mm) and lightweight (1.38 kg) it is.
The body is made of aluminium and ceramic, with Gorilla Glass on the lid. It's certainly impressive visually, but it smudges easily. There's a magnet on the top of the screen to help keep the lid closed when laid down over the keyboard, which is a good idea, although it does cause a certain amount of resistance every time you open the lid. Either way, this is top-notch manufacturing for an excellent, high-end body.
The chiclet keyboard has two levels of intensity for the backlighting and is perfectly integrated into the ceramic palm rest. The ceramic feels nice, although it's a material that's known for being fragile in the event of shocks, so you'll have to be careful with it. The keys offer comfortable, fast typing, making this a great work companion.
Like any ultrabook, this one has a cursory collection of ports: two USB 3.0, a mini-DisplayPort, a micro-HDMI out and a headphone-microphone combo jack. But Asus made up for this by including two USB adapters for VGA and Ethernet in the box. The wireless connectivity consists of Bluetooth 4.0 and Wi-Fi 802.11 AC, whose signal we measured at -47 dBm from 10 metres away and -53 dBm from 20 metres away.
The UX301LA heats up more than the UX31A (surely due to the fact that it has more powerful components inside a chassis just as thin), but it's still reasonable. The hottest point we measured while the machine was under stress was 41.9°C at the air vent located between the chassis and the display. The underside of the chassis reached a maximum of 38.1°C, so it won't get too hot on your lap. The fan stays quiet at all times, never exceeding 37 dB.
The Zenbook Prime UX31A had an outstanding screen, and this one is a tad less so, but still quite good. The UX31A's matte display has unfortunately been replaced with a glossy touchscreen here (that's some serious reflecting in the picture above). It has 2560 x 1440 resolution and the 383 cd/m² brightness and 1,095:1 contrast we measured give it excellent visibility even in bright lighting.
Grey colour temperature
It has a Delta E of 4.3, which shows that the colours aren't wildly exaggerated, but they aren't entirely faithful, either (3 and below denotes perfect accuracy, and some laptops like the 13" and 15" MacBook Pros have Delta Es as low as 2). The 8,859 K colour temperature doesn't particularly help, making for somewhat cold, bluish overtones.
The UX301LA's headphone-microphone combo jack offers satisfactory power, a succinct stereo image and no interference or background noise.
The speakers are no miracle-workers, but they'll get you through a videoconference just fine. Just know that (as usual with ultrabooks) any music you listen to will be reduced to the middle of the spectrum with little-to-no bass or high-end.
Note: The model we were sent to review features an Intel Core i7-4558U processor, 8 GB of RAM, an Intel Iris Graphics 5100 chipset and two 128 GB RAID 0 SSDs. The comments above refer to all versions of the Asus Zenbook Infinity UX301LA, whereas the sections below apply only to the model we tested (see inset below). Available configurations may also vary depending on the country/region in which you live.
The Intel Core i7-4558U dual-core processor ranges from 2.8 GHz to 3.3 GHz, placing it just ahead of the Core i7-4500U dual-core (1.8 GHz to 3 GHz).
This gives it an average performance about 5% faster than the i7-4500U found in the Dell Inspiron 14 7000 Series, and about 19% faster than the i5-4200U that equips the Lenovo IdeaPad Yoga 2 Pro. That said, it's still a ways behind quad-core processors like the i7-4700MQ, which is 20% faster on average. But in terms of everyday usage, it's a highly capable chipset that can handle any type of task in a reasonable span of time.
One unique thing about the Core i7-4558U is that it has an Iris 5100 graphics chipset. This GPU has 40 processing units, which is twice as much as the HD Graphics 4400 found in many similar ultrabooks, so we were expecting better gaming performance on it.
Unfortunately, despite having twice as many processing units, it only performs 10% to 15% better. It's still a night-and-day difference with a dedicated graphics card, even a mid-range one like the Nvidia GeForce GT 740M (40% better performance).
You can still play some recent titles, as long as they're ones that don't require much graphics processing power, such as FIFA 13 or Dirt 3, but even then you'll have to lower the screen resolution in order to get fluid gameplay. That said, it plays HD videos without a problem.
MOBILITY / BATTERY LIFE
The UX301LA held out 6 hours and 15 minutes during our battery test of continuous video playback in airplane mode with the screen brightness at 100 cd/m², headphones plugged in and the keyboard backlighting turned off. That's excellent battery life (although, of course, the 13" MacBook Air and Sony Vaio Duo 13 last even longer).