IDF 2014 – Intel Core M: architecture, performance, 2-in-1 designs
The tick-tock concept is very well known when it comes to Intel’s commitment of respecting Moore’s Law. Haswell was a tick having a new microarchitecture but being based on the same manufacturing process as Ivy Bridge (22nm), while Broadwell has the same basic microarchitecture but it’s based on the 2nd generation Tri-Gate manufacturing process on 14nm.
The 14nm process is highly optimized for low-voltage operation and also has a couple of tweaks for improved area scaling which is crucial for lower power and cost per transistor. Although the cost per mm2 went up because 14nm due to wafers and the need of additional masks, the total cost per transistor actually is below the projected improvement line because the dimensional scaling is better than projected (transistors takes less space on the die).
Intel Core M was announced at IFA 2014 in Berlin and is the first CPU based on the new Broadwell 14nm architecture. In this case, the architecture and manufacturing process were optimized for low operating voltage. The result is a impressive 4.5W TDP, with the partners having the liberty to set a lower limit (3W) or a higher limit (6W). While a fanless 4.5W TDP may seem slow to you, the results will pretty much shock you, as the CPU is a 2 core / 4 thread part running at a 1.3GHz base frequency with Turbo Boost up to 2.6GHz. Note that this is the same architecture that will be found on the Intel 5th Gen desktop and notebook CPUs (Core i3 / i5 / i7) that will launch early next year.
The platform architecture is very similar to the previous Haswell based parts, but extensive effort has been made for reducing the power usage and maximizing the performance. The FIVR has improved efficiency, the Turbo Boost is more responsive, new C7+ state introduced and also the PCH can also throttle when it’s not needed.
One interesting technology implemented for the integrated GPU is DCC or Duty Control Cycle which is avoiding working at high leakage settings. For example to get the same performance, DCC chooses to work 80% at 500MHz than to work 100% at 400MHz. Same result but better battery life!
Intel DPTF actively monitors the case temperature of mobile devices to avoid spoiling the comfort of the user by being too hot. To avoid this, the system automatically adjust the PL1 and PL2 levels.
Although it is a tick, Broadwell has clock-per-clock improvements when compared to Haswell due to refined microarchitecture changes that you can see in the slides. Much more important are the changes made to the integrated GPU, which is based on a highly modified architecture.
The Broadwell GT2 now has 24 EU’s (from 20 EU present in Haswell’s GT2), is DirectX 12 ready and has full support for OpenCL 2.0 and it’s heterogeneous computing. The media part of the IGP has also been improved, now it will support decode / encode and display for 4K content.
Core M will allow Intel to push on the market new tablets and 2-in-1’s, with significant better performance than it’s competitors. Remember that you have full PC compatibility, great battery life and 2 core / 4 thread performance at just 4.5W.
The CPU itself has 1.3 billion transistors, a die size of only 82 mm2 and it offers twice more performance per watt than previous generation – more than the usual 1.6x obtained until now. If we compare to the last generation, we get up to 50% more CPU performance and up to 40% more GPU performance.
To get a taste of the performance the little Core M can offer, we took a spin on a reference model made by Intel which weights only 684 grams and the CPU is configured for 6W TDP. Weighting just the PCB holding the SoC and all the other components inside the tablet we get just 35 grams…
The Core M 5Y70 processor is the fastest model inside the Core M family running at a base frequency of 1.3GHz when all cores are used and up to 2.6GHz when just one core is loaded. The integrated GPU is Intel HD 5300 (GT2) running up to 850MHz, this being the reason behind the stunning 3DMark Ice Storm Unlimited performance: 50327.
The CPU performance was measured with the highly multithreaded Cinebench R11.5 which got us a score of 2.6 which is very impressive for such a low TDP solution (for example Baytrail-M got a score of 1.5 while consuming about the same amount of power). The last test is Sun Spider 1.0.2 which measures browsing performance and the performance is the best seen yet on a tablet: 111 ms.
More tests with Intel’s Core M are yet to come, but for now I leave you in the company of a couple of new and interesting 2-in-1’s from Lenovo, HP and Acer. Who needs a tablet and a notebook when you can have this, right?