Last year ZDNet judged Lenovo's Yoga 3 Pro convertible to be 'very good'. The new 13.3-inch Yoga 900 advances the ball by a considerable margin: the characteristic 360-degree 'watchband' hinge mechanism remains, as does the sleek, lightweight ultrabook design. But with a serious uplift in processor power this premium device could be the new benchmark for other high-end ultrabook convertibles.

Convertible ultrabooks are no longer a new idea, and there are several takes on what 'convertible' actually means. On some devices -- also known as 'detachables' - the screen and keyboard separate completely, while others sport various 360-degree hinge mechanisms that allow the screen to lay flat against the keyboard, facing outwards in 'tablet' mode.

Image: Lenovo

Lenovo has come up with one of the most complex (and with 813 individual components, arguably the most over-engineered) 360-degree mechanisms in the shape of the Watchband Hinge. It's very visible, and is coloured orange, gold or silver depending on the device's lid and base colour.

Whatever you think of the aesthetics, the watchband hinge is smooth, reliable and flexible. It also clamps the lid and base sections firmly together in a feature Lenovo calls Auto Lock. In the old days some laptops had physical locks to keep the clamshell safely closed when in transit. Auto Lock does a good job in this respect - although when Lenovo says it's easy to open the laptop one-handed, we disagree: Auto Lock makes a pretty tight closure, and two hands are needed to prise the lid and base apart.

Images: Lenovo

The hinge is tight enough to hold the screen in any orientation. Lenovo suggests four modes: laptop (conventional clamshell); tablet (with the screen rotated 360 degrees and the keyboard facing outwards); stand (a sort of reverse laptop mode with the keyboard facing down and the screen facing outwards) and tent (resting on its two long edges with the screen and keyboard facing outwards).

The Yoga 900 is one of the many convertibles whose keyboard does not lock when you use these clamshell-alternative modes. It doesn't register key presses, but the keys still physically depress, which could be an issue when you're working in tablet mode with the keyboard facing outwards. Although the Yoga 900 is an ultrabook and therefore relatively lightweight at 1.29kg, there's still a fair bit of weight to hold in one or two hands. The pressure on keys when doing this is not insubstantial, and certainly greater than when typing. We're always concerned about mid- to long-term keyboard issues with such devices.

Thin and light is the name of the game here, and at 1.49cm thick the Yoga 900 slips easily into a bag. The metal base and lid are not especially scratch resistant, but they certainly make for a rigid laptop that should travel well without a protective case.

The Yoga 900's desktop footprint of 32.4cm wide by 22.5cm deep is not unreasonable for a 13.3-inch laptop that requires a fair sized bezel to cater for tablet mode. That said, when working in laptop mode the hefty near-30mm bottom bezel housing the Windows button is particularly noticeable.

The screen itself is wonderful. The 3,200-by-1,800 pixel IPS panel is bright and sharp with very vibrant colours. It's the same 276 pixel-per-inch (ppi) resolution as its Yoga 3 Pro predecessor, but we're more than happy with the quality it delivers. Viewing angles are very good, and the only downside that it's quite reflective.

There's a button on the right side of the chassis that toggles the screen rotation lock. Inexplicably, using this caused a couple of problems with our review sample, which failed to resume autorotation unless restarted. These glitches coincided with a greyed-out on-screen rotation control, so maybe there's a software issue for Lenovo to iron out here.

If you want to use your laptop for work presentations or a bit of leisure entertainment you'll appreciate the 1.5W JBL speakers, which deliver high- quality sound at loud enough volume to reach across a decent-sized conference table.

Image: Lenovo

The backlit keyboard has a very light touch indeed -- keys barely depress as you tap away at them. We like Lenovo's minimal approach here and found touch typing speedy and efficient, but it won't appeal to everyone. There's a soft-touch rubbery finish round the keyboard that provides a nice rest for the wrists -- and also helps with grip when you're holding the Yoga 900 in tablet mode.

Last year's Yoga 3 Pro lacked a Fn key row above the number keys, and we're pleased to see it return in the Yoga 900. These keys also house a range of shortcuts, including volume and screen brightness controls, switching to external displays and popping into flight mode, and it's great to see them back as easy, single-keypress actions.

Various versions of the Windows 10-based Yoga 900 are available, based around 6th-generation Intel Core i7-6500U or Core i5-6200U processors. Models on sale in the UK as we write come with 8GB of RAM and a 256GB SSD, although our review sample had a 16GB and a 512GB SSD alongside the Core i7 processor.

Lenovo has boosted the battery capacity considerably from 44WHr in the Yoga 3 Pro, claiming up to 9 hours' life from the Yoga 900's 66WHr battery. Our real-world testing suggests that's a tad optimistic, although many less demanding users will stand a good chance of all-day computing from a full battery.

Lenovo uses a metal-alloy fan, with cooling vents built into the hinge. These explain why the hinge feels slightly warm to the touch even when the Yoga 900 is idle. The warmth is not a problem, just an interesting approach to heat dissipation.

Image: Lenovo

Wi-fi (dual-band 802.11ac) and Bluetooth (4.0) are supported, as you'd expect, but there's no NFC or mobile broadband. Connections comprise a single USB-C port that supports video out, two USB 3.0 ports and a USB 2.0 port which doubles as the power connector. There's also a flash card reader and a headset jack. It's a minimal set for those who hanker for the likes of HDMI or DisplayPort, but it is functional.

Following last year's Superfish adware debacle, the Yoga 900 has an admirably lightweight software bundle. McAfee LiveSafe is here, along with a few Lenovo apps including Lenovo Photo Master and Lenovo Companion, which is a route to device support and optimisation.

Conclusions

This is an excellent ultrabook featuring high-end processors, a great screen, good audio and exemplary build quality. The watchband hinge may be quirky but it works well, and there's even a 512GB SSD option for those who need it. Just be a little wary of the 9-hour battery life claim.

In the UK, the Yoga costs £1,199.95 (inc. VAT/£995.83 ex. VAT) for a Core i5/8GB/256GB model, or £1,299.95 (inc. VAT/1,083.29 ex. VAT) for a Core i7/8GB/256GB configuration.

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