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Asus' Transformer Book T300 Chi convertible reviewed

Core M horsepower in a detachable 2-in-1

I've been waiting almost a year to review Asus' Transformer Book T300 Chi—ever since company Chairman Johnny Shih teased the slender convertible before last year's Computex show. Can you blame me? The Chi promises a full-fat Windows experience powered by a Broadwell processor and a high-PPI 12.5" IPS display. The tablet component is thinner than an iPad Air, and it ships with a keyboard that attaches with magnets, turning the device into notebook-like clamshell.

The Chi isn't all Asus' doing. One day after the system's initial reveal, Intel introduced the Core M processor behind it. Otherwise known as Broadwell-Y, this ultra-low-power variant of the CPU giant's latest microarchitecture was designed specifically for fanless 2-in-1 devices like the Transformer. It occupies a middle ground between the lower-power Atom chips found in entry-level machines and the higher-wattage Broadwell-U silicon reserved for ultrabooks.

In a lot of ways, the Core M is reminiscent of the Consumer Ultra-Low-Voltage Pentium in my old ultraportable notebook. That CULV CPU split the difference between the Atom and Core processors of its era to enable a nascent class of affordable ultraportables. This time around, a similar formula is being used to enable the budding category of slim convertibles.

That brings me to the other reason I've been dying to get my hands on the T300 Chi. I'm in the market for a convertible to replace my aging CULV workhorse, and the new Transformer is one of the leading candidates. This review is much more than just a test drive, then. It's a personal audition with my own money at stake.

A lot of the Transformer's appeal stems from its affordable pricing. The entry-level T300 Chi starts at $699, which gets you a Core M-5Y10 processor, 1080p display, and 4GB of RAM. Asus sent us a more upscale version, the T300CHI-FH011H, endowed with a faster Core M-5Y71 chip, a higher-resolution 2560x1440 screen, and double the memory. This "limited-run" model is available exclusively through Asus' online store for $899.

Both processor options have dual cores and quad threads. They're fabbed on the latest 14-nm process, just like the rest of the Broadwell family, but they operate within a much tighter 4.5W thermal envelope. Scott's in-depth look at the Core M covers everything you need to know about the chip, so I won't rehash all the gory details here.

The 5Y10 is clocked at 800MHz base and 2GHz Turbo, while the top-of-the-line 5Y71 starts at 1.2GHz and scales up to 2.9GHz. There are differences in the integrated graphics frequencies, as well. The onboard HD 5300 GPU ranges from 100-850MHz in the 5Y10 and from 300-900MHz in the flagship. This "GT2" variant of Broadwell's GPU is the same as in ultrabook-class parts.

Both Core M chips sport dual-channel memory controllers, but the Chi's base configuration hangs its 4GB of RAM off only one channel, effectively halving the bandwidth available to the processor. That's bad news for graphics performance, which tends to be very sensitive to memory bandwidth. Fortunately, the higher-end unit we tested spreads double the memory across dual channels. The full system specs are listed below.

  Transformer Book T300 Chi
Model T300CHI-FH011H
Processor Intel Core M 5Y71
Display 12.5" IPS 2560x1440
System RAM 8GB LPDDR3-1600
Storage 128GB internal SanDisk iSSD
Micro SDXC slot
Camera HD webcam (front)
Wireless 802.11a/b/g/n/ac
Bluetooth 4.0
I/O ports Micro USB 3.0
Micro HDMI
3.5-mm headset
Battery 32 WHr
Dimensions 12.5" x 7.5" x 0.65"/318 x 192 x 16.5 mm
12.5" x 7.5" x 0.3"/318 x 192 x 7.6 mm (tablet)
Weight 3.2 lbs/1.5 kg
1.6 lbs/0.73 kg (tablet)
Operating system Windows 8.1 x64

On the storage front, each T300 incarnation comes with a 128GB SanDisk iSSD. This single-chip SATA drive has an SLC cache to accelerate write performance, and it should be quicker than the eMMC alternatives found in some cheaper tablets. 15GB is monopolized by a recovery partition, while Windows and the handful of pre-installed applications chews through another 10GB. Users can bolster the onboard flash via the Micro SDXC slot tucked into the tablet's edge.

I've now broken one of the new rules of tech journalism by discussing a bunch of nerdy specs before talking about the look and feel of the device. But that was intentional, because understanding the potency of the hardware is crucial to fully appreciating the lithe chassis wrapped around it.

At only 0.3" (7.6 mm) thick, the Transformer's tablet component cuts a slimmer profile than plenty of slates based on much less capable hardware. The accompanying keyboard dock bumps the thickness up to 0.65" (16.5 mm), which is still slender enough for ultrabook classification.

Skinny frame aside, the T300 is no featherweight. At 1.6 lbs (0.73 kg), the tablet is twice the weight of the iPad Air. That's a big difference if you're cradling the tablet in one hand, especially for prolonged periods. Adding the keyboard doubles the heft, but the resulting clamshell doesn't feel too heavy when perched on my lap or tucked under my arm.

There's also the not-so-small matter of the Chi's oversized footprint. The 12.5" screen obviously requires a jumbo frame, but fat left and right bezels make the T300 an extra-wide load. To put things in perspective, look at how the system compares to Asus' Transformer Book T100 convertible, whose smaller 10.1" screen has the same aspect ratio as the Chi's larger display.

The additional width doesn't hamper the Chi's portability, but it does make the system feel larger than the screen size suggests. The Chi is only marginally narrower than Asus' ZenBook UX305, which has similarly slim proportions but a 13.3" display. Perhaps wider bezels are necessary to accommodate the ports perforating the tablet's exterior.

The right edge hosts Micro HDMI and USB ports along with an analog audio jack. The Micro SD slot is just around the corner, while the power jack lives on the other side. There's a separate Micro USB port in the keyboard, as well. More on that in a moment.

Asus puts the power switch on the top edge and the volume and Windows buttons on the left. That arrangement works well for landscape orientations, but it's a bit of a reach in portrait mode due to the large screen. All the buttons provide good tactile feedback with a discernable click.

Tiny breathing holes line the tablet's left and right edges, but they're not backed by a blower. The T300 Chi is completely fanless, ensuring silent operation regardless of the load. The holes are actually for the integrated speakers, whose output is reasonably loud but short on bass. Bring headphones if you want better sound quality—and maybe a USB DAC if you're especially picky. Audio piped through the analog jack sounds fine, just no better than that.

The last couple images provide a nice view of the T300's sleek body. The tablet's unibody aluminum shell feels sturdy, with little flex and seemingly solid build quality. Diamond-cut edges add a touch of flare to the otherwise understated design. They also fuel a clever illusion. The highlighted edges slope subtly toward the front, making the Chi appear thinner at that end. In reality, the tablet is the same thickness throughout.

As much as I like the Chi's matte charcoal finish, it has a tendency to accumulate smudges with everyday handling. Those blemishes aren't as bad as what we've encountered on systems with glossy skin, and you can buff them out with the cleaning cloth included in the box. The surface also seems reasonably resistant to scratches.

Even when sullied by the splotchy remnants of my fingertips, the exterior looks attractive without seeking attention. It's pleasantly smooth and slightly soft to the touch, conveying a premium feel that belies the $699 starting price.

Unlike with some Windows tablets, that asking price includes a keyboard. In some ways, this sidekick is a whole 'nother animal compared to the keyboard docks attached to previous Transformers. The next page explains why.