In Depth: Why you're getting more out of AMD and Intel's smaller processors ~ lotfi

The mobile processor arms race is back on as both Intel and AMD have unveiled smaller processors at the of start 2015. Intel kicked things off by introducing 14nm Broadwell, a miniaturization of the company's already efficient 24nm Haswell architecture, at CES 2015. Not to be forgotten, AMD announced its 28nm Carrizo architecture on February 21, claiming it found a way to squeeze 29% more transistors into the same space as its older processors.

Although it might seem like Intel has the leg up on AMD with a smaller manufacturing process, both companies have essentially created a shrunken CPU core. There are big benefits to be had from going smaller as these components draw less power and invariably produce less heat.

This potentially paves the way for thinner and longer-lasting laptops, similar to what Intel's Core M chip has done for fanless laptops like the Asus ZenBook UX305. So without further ado let's dive into two chipmakers are tackling smaller processors and the benefits you can expect this CPU generation.

Intel Broadwell and AMD Carrizo

Why Intel downsized

When we say CPUs are shrinking, the chip itself isn't the only thing getting smaller. Invisible to the naked eye, the underlying transistors that make up the processors' brains became even tinnier.

Intel's Mobile Marketing Manager Karen Regis said that with Broadwell, the company found a way to mince its 22nm Haswell transistors into even finer 14nm bits. Despite making the processor die smaller, Intel was able to fit more transistors. This was thanks to reducing the size of everything else on the CPU, from the transistor pins to the gates to the interconnecting material holding the part together in 13-layers.

In doing so, Intel claimed it was able to increase Broadwell's power efficiency by 30%. The new CPUs use less energy thanks to being inherently smaller and having better built-in power management for a laptop's other components.

"We can help to reduce the power consumption across other components in the platform like, say, memory," Regis said of the benefits of Broadwell's improved power management.

Intel Broadwell and AMD Carrizo

In our own benchmark testing we found an Intel Core i5 Broadwell-powered Dell XPS 13 was able to perform on equal footing with last year's model, which came sporting a higher-end Core i7 processor. Battery life also saw a considerable bump from 3 hours and 47 minutes to 4 hours and 21 minutes.

While that's closer to a 15% increase in battery life, users upgrading to new Broadwell-powered machines should see a net increase in battery life from Haswell-powered machines..

Even smaller and lower-wattage CPUs like Intel's Core M processor have enabled manufacturers to come out with thinner, lighter and longer-lasting laptops. The Lenovo Yoga 3 Pro and Asus ZenBook UX305 are two such laptops that offer users the full Windows 8.1 experience on a machine that lasts just over five hours.

Broadwell's other advantages

Energy efficiency isn't the only trick Broadwell has up its sleeve. With its latest mobile processor refresh, Intel also improved the on-board integrated graphics. Broadwell features a shrunken GPU die, which allowed Intel to attach more graphics execution units responsible for driving the visuals on the laptop to deliver better performance.

Additionally, the processor maker increased the peak frequency on its graphics engine. All in all these improvements should allow even small form-factor devices without the space for a discrete graphics to perform exceptionally well with graphics-intensive applications and games.

Intel Broadwell and AMD Carrizo

What is AMD Carizzo?

While it's pretty easy to explain Broadwell as a new processor with smaller transistors, AMD's new Carrizo chips are slightly more complicated. To make its more efficient parts, AMD opted to stick with 28nm transistors and arranged them into a more tightly wound bundle made of eight layers.

AMD Corporate Fellow Sam Naffziger explained why tightening up is a good thing, revealing the chip maker's engineers managed to pack in 29% more transistors on Carrizo.

"There is some benefit from shrinking everything because distances [between transistors] are shorter, there's less metal for power to travel across and the gates are smaller," he said.

This means there's less voltage being lost in translation between the processor's transistors. A few tiny charges of electricity might not sound like a lot, but they add up and Carrizo should let laptops squeeze out a bit more battery life than AMD's current A-series of APU processors.

The heat issue

However, Naffziger also noted that, "by packing things more closely, you increase the power density.

"You're just jamming more circuity into the same area and if it's generating the same level of activity, it could get hotter even if it's just burning the same amount of power," he cautioned.

To design around the issue, Naffziger said the team at AMD took care to space the CPU cores accordingly. Every core was moved away from one another and the edges of the processor die to prevent the component from getting any hotter than its A-series predecessor.

Of course, we won't know how successful AMD was at reducing heat until we test Carrizo in a laptop. As we've seen with thin gaming laptops such as the Aorus X7 Pro, even a well-engineered cooling system can't keep up with rip-roaring parts, so there's still the potential Carrizo could be a seriously hot potato when it starts arriving in notebooks.

Intel Broadwell and AMD Carrizo

Mind the droop

As for power savings, AMD expects Carrizo to consume 40% less power than its A-series APUs. Naffziger explained AMD's latest CPU technology utilizes multiple approaches to reduce power needs.

Aside from the inherently decreased power needs of a smaller microarchitecture, the AMD team gated clock processor speed aggressively to prevent the CPU cores from running unnecessarily fast and chewing through battery life.

More importantly, Carrizo focuses on saving power that goes to the CPU and GPU through voltage optimization. Carrizo also drops the processor frequency rate when voltage flowing to the chip's CPU and GPU falls out of spec, otherwise known as a "droop." Typically when processors experience a droop, they have to compensate for the loss of power by introducing more voltage and wasting energy.

Naffziger said the company isn't ready to give exact estimates but power-saving optimizations should amount to improved battery life stretching into double-digit minutes that border on triple digits. This is thanks to aggressive optimizations that turn everything off on the processor diode, which should help reduce power draw when your notebook is on idle or you're using low-resource applications like Microsoft Word.

What's more, Carrizo will be one of the first processors to feature hardware decode to better handle streaming video and save multiple watts of power in the CPU. For gaming, Carrizo will support Mantle and DirectX 12.

When and in what devices will it get here?

Intel hasn't been shy about its plans to fully launch Broadwell on all future notebooks and mobile devices. At CES 2015, the chip maker announced it would release Broadwell parts across its entire CPU line-up, from low-voltage Core M and Celeron processors all the way to gaming machine-grade Core i7 chips. Many of these laptops are on their way to full commercial releases.

Similarly, AMD plans to push Carrizo out in a wide release, though it has yet to announce a release window. However, when it does arrive it will fill out the 12- to 35-watt notebook space. This includes everything from budget laptops to systems with comparable performance to an Intel Core i5 chip.

Sadly, even the lowest wattage processors won't even scratch the 5-watt range of Intel's Core M-powered laptops, so don't expect to see any fanless configurations with Carrizo until AMD announces a processor that's even more lightweight.

Intel's new, smaller Broadwell architecture has already spawned a new series of smaller and lighter laptops, including the Dell XPS 13. We have every expectation AMD's new Carrizo processors will do the same as all signs point to more compact and longer-lasting laptops.