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A peek at Intel Core M tablet performance (14nm Broadwell)

by Tarinder Sandhu on 11 September 2014, 02:15

Tags: Intel (NASDAQ:INTC)

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Intel took the lid off the next-generation Broadwell microarchitecture last week. Though you can read more about it here, Broadwell offers minor CPU-side performance benefits over Haswell but improves graphics potential a notch or two by adding in more shading cores and texturing throughput.

But Broadwell's greatest trick is in reducing energy consumption by a healthy degree when compared to Haswell, made possible by a combination of switching to a 14nm manufacturing process, down from 22nm, and architecture redesign that, across the board, focusses on reducing power draw at every corner. Broadwell's power consumption, or lack thereof, is arguably more important than pure performance.

The sum of these efforts is encapsulated in the Broadwell-based Core M chip. Available in fanless 2-in-1 computers and premium tablets from next month, the processor has a 4.5W TDP, reduced from 11.5W on the equivalent Haswell Core i5-4210Y model.

Llama Mountain

So just how potent is the next-gen Core architecture when limited to 4.5W? To find out, Intel held a controlled benchmarking session at IDF 2014.

The range-topping Core M 5Y70 processor was housed inside a tablet featuring an Intel reference platform known as Llama Mountain. Using a 12.5in screen with a 2,560x1,440 resolution, the 670g tablet is 7.4mm thin. The Broadwell processor features a configurable TDP, from 3W to 6W, but Intel chose to run it at the default 4.5W, meaning fanless operation. Boosting up to 2.6GHz on the CPU and 850MHz on the GPU, the tablet was smooth and fast in Windows 8.1.

Inside, a tiny motherboard houses the Broadwell processor, platform controller hub and device memory. A connected card provides storage through NAND flash and WiFi connectivity. Presenting a potential wrinkle, Broadwell processors use the second-generation fully-integrated voltage regulator that requires inductors to be placed on to the package. Intel has managed to keep the height of the chip low - and, therefore, tablets and 2-in-1s thin - by using special packaging that enables these inductors to sit underneath the processor on an external PCB. The upshot of this is that the motherboard has a cutout for this additional PCB.

Device manufacturers have been provided guidelines on how best to implement Core M into thin devices, but it will be up to each to determine the best compromise between performance and energy efficiency.

Core power

Firing up the CPU's dual cores and four threads first - which, remember, are a little more efficient than Haswell's - the Llama Mountain tablet returned a Cinebench R11.5 score of 2.75. We use the newer Cinebench R15 in reviews, but referencing older reviews shows it to be only 20 per cent slower than a desktop Core i3-3225 equipped with a 55W TDP; impressive given the Core M 5Y70's meagre power budget that is less than one-tenth the Core i3's. Certainly quick enough for everyday tasks. Compared to a mobile-orientated processor, the score is a touch better than the 2.5 achieved by the Haswell-based Core i5-4250U powering the second-generation NUC.

Switching gears to the HD 5300 GPU, which houses a reworked architecture from Haswell, the 24-EU part cranked out a 3DMark Ice Storm Unlimited score of over 50,000, or 60 per cent faster than that achieved by the latest Tegra K1 GPU inside the Nvidia Shield tablet.

A 3DMark Firestrike score of 522 was also significantly better than the Core i5-4210Y Haswell's 309, though short of the 771 achieved by the 40-EU Intel HD 5000 Graphics contained within the 15W Core i5-4250U. Put simply, the 4.5W Broadwell processor performs like the best 10W-15W parts from the current Haswell generation.

Desktop-like performance?

Intel claims a performance leadership position in the fanless tablet category with the Core M chip, citing a 3x CPU and 2x GPU speedup when compared against a Qualcomm Snapdragon 805-powered device. Being even-handed, that GPU performance lead isn't as great when Nvidia's Tegra K1 is thrown into the mix, however, and the CPU assertion may not stand up to scrutiny if the latest high-end ARM Cortex A-series architecture is taken into account.

Yet comparing against other available tablets is a tad misleading. The Core M is designed to run Windows rather than Android. More pressing, the significantly higher cost of the Broadwell processors - Haswell 4210Y, as a comparison, is $281 for the SoC alone - means that Core M-totin' tablets and 2-in-1s are likely to be priced much higher than ARM-based devices.

Economic ramifications aside, the Core M processor provides desktop-like performance in a fanless, super-slim form factor.

HEXUS Forums :: 9 Comments

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This is the actual benchmark run by an Intel employee on a Core M tablet:


You might notice something weird about the benchmark run,especially consider it does not appear to be edited.

Did Hexus see the same??


Supposedly that mode is run off screen - but did anyone actual see any ACTUAL graphics being rendered and if not is there any chance of you checking it out.
So are we likely to start seeing tablets with full fat versions of windows? Including the same sort of connectivity e.g. external hdd's, mouse, keyboard, USB sticks etc?
Some posters over on Anandtech forums noticed some interesting points.

Hans de Vries
Intel's Fastest Processor Ever…..and the Burst Mode Trick.

The tiny “4.5W” Core M seemingly humiliates the previous record holders,
including the Core i7 4790 Devil's Canyon running at a burst speed of 4.4GHz.

I guess we will see many claim that Intel's new 14nm process is now 20
times more power efficient as Intel's 22nm process or similar wild claims.
(Even though Intel itself never made such outrageous claims of course)

Those who know how Intel's Burst Mode work will understand how you
can produce these kind of miraculous benchmark result. They will wonder
instead if the new F-stepping can now officially be boosted to 4+GHz
for very short periods of time.

Here's explained how it works:

The figure at the bottom right with the three blue spikes explains it all.
The blue spikes mean that the processor is running at maximum frequency
while during the intervals the processor is basically halted.

Say with a single active core Broadwell at 14nm, running a 4+GHz requires
~18 Watt (would be very good!).

A power dissipation of 4.5 Watt would mean that the processor is bursting
at maximum frequency during 25% of the time and idle during 75% of the
time to cool down.

You can't measure this at the outside of the package because the on-
package voltage regulators and capacitors take care of the large power
and current spikes. From the outside you only see a processor using
4.5 Watt.

The benchmark can't see this either. It measures the “process-time”
when the processor is active and running at maximum frequency.
The benchmark doesn't measure the time when the processor is idle
and cooling down. Therefor you get a benchmark result as if the
processor is running always at maximum burst frequency.


There is also the problem of whether the sw stack is also helping inflate scores over existing reviews too.

This copper plate makes direct contact with the aluminum housing of the tablet, so essentially the table housing itself is one gigantic heatsink.

The heatsink of the reference tablet is massive.

I think we need some third party reviews first of production Core M tablets first - it looks a decent performing SOC,but I would rather see realworld performance first.
So are we likely to start seeing tablets with full fat versions of windows? Including the same sort of connectivity e.g. external hdd's, mouse, keyboard, USB sticks etc?
Erm, I thought we already had those - at least as a “convertible” like the Asus T100.
PS My three-year old Android-toting TF101 tablet (bought from Comet - remember them?) supports USB hdds and sticks and I've tried it (successfully) with a Logitech wireless USB keyboard. Downside is that you need to have it docked to get more than one USB port.
Using a 12.5in screen with a 2,560x1,440 resolution, the 670g tablet is 7.4mm thin.
:redcard: Think you mean “7.4mm thick”, as we talk about the “thickness” of something, not “thinness”. Unless, of course, you're an American, in which case there's no hope for you…
Be interesting when these are actually in devices to get real world results. These look very skewed!

So are we likely to start seeing tablets with full fat versions of windows? Including the same sort of connectivity e.g. external hdd's, mouse, keyboard, USB sticks etc?

You can already get full fat Windows 8 tablets such as the Dell Venue 8 Pro.
It's got a mini USB port, so can use all your normal usb devices, attach a hub for expansion.
(Just needs an OTG cable, couple of pound on amazon/ebay)

The only trouble with the Venue 8 Pro is the USB port is also used for charging and it takes some messing to get charging+usb devices to work at the same time. Otherwise its one or the other.

I've used several of these in work, and very good unit for the price! (About Ā£180)