Intel's Broadwell-U arrives aboard 15W, 28W mobile processors


— 9:00 AM on January 5, 2015

Fresh from its debut in the 4.5W Core M series last fall, Intel's Broadwell architecture has landed in 17 new processors with 15W and 28W power envelopes. The branding for these arrivals is a little confusing—some belong to the 5th Generation Core family, which weirdly doesn't include the Core M, while others carry Pentium and Celeron monikers—but all are easily identifiable by their code name: Broadwell-U.

Where Broadwell-Y, also known as the Core M, is aimed mostly at tablets, small-screen convertibles, and ultra-thin laptops, Broadwell-U is expected to appear in a "broad range of form factors." Among those: larger convertible notebooks, more traditional laptops, and some desktop systems, particularly all-in-one and small-form-factor designs.


Source: Intel

About half of the Broadwell-U family is based on the chip pictured above, the same one that drives the Core M. This die has 1.3 billion transistors and an 82 mm² footprint, making it smaller and denser than last year's Haswell-U silicon.

Intel is quoting some nice performance and battery-life improvements this time around, as the slide above shows. Battery run times are especially improved in video playback, thanks in part to the SmartSound audio DSP built into Broadwell-U. Performance in productivity tasks hasn't improved very much, Intel says, because Broadwell is a "tick" rather than a "tock" on its roadmap—that is, Broadwell's CPU cores are shrunken versions of their Haswell counterparts. We won't see a new CPU architecture from Intel until the next "tock," Skylake, which is due out later this year.

The remainder of the Broadwell-U lineup is based on a bigger chip that allocates a larger transistor budget to graphics:

This jumbo version of Broadwell-U bumps the transistor count to 1.9 billion and the die area to 133 mm². There are still two CPU cores, and the amount of L3 cache is unchanged, at 4MB, but the integrated graphics have twice are many execution units (EUs) as on the smaller die, for a total of 48.

Intel will denote this silicon with HD Graphics 6000 branding on 15W processors and Iris Graphics 6100 branding on 28W parts. Compared to the "baseline" HD Graphics 5500 offered in the smaller die, Intel says users can expect an increase in performance of up to 20% with the HD Graphics 6000 and up to 50% with the Iris Graphics 6100—and all without the use of on-package eDRAM. Only processors with Iris Pro graphics will have eDRAM, and Intel hasn't announced those yet.

Here's a look at the Broadwell-U lineup, starting with 15W CPUs:

Model Cores/
threads
Base
speed
(GHz)
Max Turbo
speed (GHz)
Intel HD
Graphics
Base/max
graphics
speed
(MHz)
Max
LPDDR3
speed
(MT/s)
L3
cache
cTDP
down
Price
1 core 2 cores
Core i7-5650U 2/4 2.2 3.2 3.1 6000 300/1000 1866 4MB 9.5W $426
Core i7-5600U 2/4 2.6 3.2 3.1 5500 300/950 1600 4MB 7.5W $393
Core i7-5550U 2/4 2.0 3.0 2.9 6000 300/1000 1866 4MB 9.5W $426
Core i7-5500U 2/4 2.4 3.0 2.9 5500 300/950 1600 4MB 7.5W $393
Core i5-5350U 2/4 1.8 2.9 2.7 6000 300/1000 1866 3MB 9.5W $315
Core i5-5300U 2/4 2.3 2.9 2.7 5500 300/900 1600 3MB 7.5W $281
Core i5-5250U 2/4 1.6 2.7 2.5 6000 300/950 1866 3MB 9.5W $315
Core i5-5200U 2/4 2.2 2.7 2.5 5500 300/900 1600 3MB 7.5W $281
Core i3-5010U 2/4 2.1 N/A N/A 5500 300/900 1600 3MB 10W $281
Core i3-5005U 2/4 2.0 N/A N/A 5500 300/850 1600 3MB 10W $275
Pentium 3805U 2/2 1.9 N/A N/A - 100/800 1600 2MB 10W $161
Celeron 3755U 2/2 1.7 N/A N/A - 100/800 1600 2MB 10W $107
Celeron 3205U 2/2 1.5 N/A N/A - 100/800 1600 2MB 10W $107

Note the "cTDP down" numbers. While these chips all have 15W TDP ratings, they can also be configured to fit inside smaller power envelopes. It looks like only processors based on the smaller die can squeeze into a 7.5W TDP, though. The jumbo die only goes down to 9.5W.

Such TDP reductions will entail corresponding reductions in base clocks. Intel isn't sharing much in the way of specifics there, but it does say the peak single-core Turbo speeds quoted above apply regardless of the TDP setting.

Thanks to the chipmaker's product segmentation voodoo, vPro and TXT support is exclusive to just four products: the Core i7-5650U, i7-5600U, i5-5350U, and i5-5300U. Also, AES-NI support is missing from the Pentium and Celeron parts, and the maximum supported LPDDR3 memory speed is higher on chips with the jumbo die. All Broadwell-U processors announced today are limited to 1600 MT/s when using DDR3L memory, though.

By the way, don't misconstrue the table above: Pentium and Celeron parts aren't bereft of integrated graphics. Intel simply gives their IGPs plain "HD Graphics" branding without model numbers. That moniker denotes the presence of only 12 graphics EUs—half as many as on the HD Graphics 5500—plus lower base and peak graphics clocks.

Now, here are the 28W incarnations of Broadwell-U:

Model Cores/
threads
Base
speed
(GHz)
Max Turbo
speed (GHz)
Intel Iris
Graphics
Base/max
graphics
speed
(MHz)
Max
LPDDR3
speed
(MT/s)
L3
cache
cTDP
down
Price
1 core 2 cores
Core i7-5557U 2/4 3.1 3.4 3.4 6100 300/1100 1866 4MB 23W $426
Core i5-5287U 2/4 2.9 3.3 3.3 6100 300/1100 1866 3MB 23W $315
Core i5-5257U 2/4 2.7 3.1 3.1 6100 300/1050 1866 3MB 23W $315
Core i3-5157U 2/4 2.5 N/A N/A 6100 300/1000 1866 3MB 23W $315

The base clock speeds are higher here, as are graphics clocks. Intel's cTDP mojo also allows power envelopes to be configured down from 28W to 23W across the board. And no, none of these processors support either vPro or TXT. Corporate customers will have to go with one of the 15W parts if they want those features.

Intel expects the first Broadwell-U-based systems to appear "online and on shelf" on January 18. Machines powered by the jumbo die will be a "little bit behind." (Intel says models with Iris graphics won't hit the market until "later on in the first quarter.") We can look forward to the first Broadwell-U-powered Chromebooks in February, as well.

For several reasons, Intel believes the Broadwell-U rollout will be its "fastest mobile transition ever." This is the first time the chipmaker has launched corporate and consumer offerings together, and it's also the first time Pentium and Celeron processors have come out alongside with their Core counterparts. Broadwell-U chips are priced similarly to their predecessors, and they're compatible with the same motherboards. Intel says we'll see "some chassis reuse" along with some "cool new designs."

Speaking of new designs, there's more to this launch than just processors. The Broadwell-U generational refresh represents the "start of the ramp" for RealSense and Wireless Gigabit technologies, Intel says. The company also foresees "wide deployment" of its Wireless Display technology this generation. The latest flavor of that technology, WiDi 5.1, adds support for business-friendly security and management features, full-screen DirectX 9 and DirectX 11 gaming, and display resolutions up to 4K. A new adapter compatible with WiDi 5.1, Actiontec's Mini2, recently became available for just $39.99.

What's next? Now that Broadwell-U is out, Intel still needs to fill out the Broadwell lineup with higher-wattage mobile and desktop parts. The company provided a rough timeline for those, saying Broadwell chips with thermal envelopes greater than 45W, including some quad-core models, will be out for desktops and notebooks in mid-2015. Offerings with Iris Pro graphics are scheduled for the same time frame, as well.

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