Y has it taken so long for Intel to get its u boat out the door? Mark Williams deep dives into the latest CPU release from Intel.
Fifth generation Broadwell CPUs from Intel are already out in the form on its Core M line up (aka Broadwell-Y) which are at the lower performance end of Intel’s product stack (any lower and you’re into Intel’s Atom range), Broadwell-Y is aimed at low power solutions like tablets, 2-in-1 tablet convertibles and fanless Ultrabook designs.
Broadwell-U however, which Intel launched at the recent Consumer Electronics Show, is the first of Intel’s 5th generation Core CPUs that the average consumer will likely get their hands on and sits in the middle of its intended BGA packaged line up.
The next step up in power from Broadwell-Y (4.5W max) and still only dual core, Broadwell-U (15-28W max) is aimed at mid to high end Ultrabooks and other thinand-light or low end laptops, even into small integrated desktop solutions like Intel’s NUC or Gigabyte Brix-type products.
HONEY, I SHRUNK THE CHIPS!
Intel is having a tougher time producing these CPUs as it initially struggled to refine its new 14nm (nanometre) manufacturing process to achieve acceptable yields. Broadwell’s launch was pushed back early on and in what would normally happen in around 6-8 months, the launch of this new generation of mainstream CPUs is going to take around 10 months. Broadwell-Y launched back in September of last year, Broadwell-U is just launching now, and the highest tier quad core BGA Broadwell-H (47W max) CPUs and 1150 socketed desktop Broadwell-K parts are currently projected for a mid-2015 release. The extended launch window shows how hard it’s starting to become with each new node shrink.
Node shrinks, the “tick” in Intel’s “ticktock” release cadence (“tock” being new architecture releases), as with Intel’s new world leading 14nm process do however afford benefits all of its own despite no under the hood architectural changes having to take place. Node shrinks mean less voltage is required for the silicon to operate, providing power and heat savings and thus cooler and longer lasting devices.
As the die size physically shrinks down too it also allows manufactures to utilise the saved die space to add in even more transistors thus allowing them to add more grunt for free. Which is the case with Broadwell-U.
NUTS AND BOLTS
Broadwell-U is being manufactured as just two chips from which all the variants will be derived from. One is larger in size due to having more dedicated graphics transistors on board for its “GT3” IGPs, see the image above while the smaller one powers the rest of the line-up with “GT2” and “GT1” IGPs, but more on that later.
Thanks to the 14nm node, compared to the previous generation Haswell-U (22nm process) GT3 equipped CPUs, Broadwell-U has shrunk down 26% to 133mm2 despite packing in over a massive 46% more transistors, 1.9 billion total! The figures for the leaner GT2 and GT1 IGPed versions are equally impressive too, down a huge 37% in die size (82mm2) and includes an increase of 35% more transistors for 1.3 billion total.
Despite all these new transistors, the idle power consumption of these 5th gen chips has dropped all the same. Where the 4th generation was around 9.5W to 11.5W, Broadwell-U has dropped down to 7.5W to 9.5W at idle and it has Intel claiming that it’ll extend battery life by around 60 to 90 minutes overall.
Interestingly Broadwell-U will be maintaining pin compatibility with Haswell-U, meaning manufacturers, should they decide, could drop these new processors into existing product designs for a cheap and easy product line refresh, all that’s needed is a simple firmware update.
THE BRAINS
Despite the new manufacturing node giving Intel thermal headroom aplenty to play with they haven’t upped the peak frequencies these CPUs will be running at. Haswell-U topped out at 3.5GHz with the i7 4578U. Broadwell-U on the other hand, at least with what’s currently been launched, only tops out at 3.4GHz on the i7 5557U which is partly why Intel is claiming the extra battery life statistics. However where Broadwell-U is improving is with the base clocks, the i7 5557U has a base clock of 3.1GHz compared to 3.0GHz on the i7 4578U. This trend continues across the whole line up, basically matching peak clock speeds of the 4th generation processors while getting a 100-300MHz speed bump on the base clocks, even up to an extra 600MHz in the case of the i7 5500U versus the i7 4500U.
The move to 14nm doesn’t appear to be just a ‘dumb’ die shrink either, Intel is claiming a 5% Instructions Per Clock (IPC) improvement thanks to a few tweaks, mostly to do with scheduler and buffer optimisations amongst other things, giving these 5th-gen parts an edge despite similar or 3% lower peak clocks.
THE BRAWN
5% IPC boost for the CPU is nothing to scoff at, but when you’re claiming 22% improvement to graphics, that’s much more impressive indeed.
All those extra transistors mentioned earlier have been mostly spent beefing up the graphics processor’s execution units (EUs). The larger GT3 powered chip now sports 48 EUs compared to Haswell-U’s 40 EUs and takes up a massive two thirds of the die space, while the smaller GT2/GT1 powered chip with 24 EU’s total compared to the previous generations 20EUs, a solid 20% uptick in GPU resources, take up half the die space.
Any model you see in the table above with a ‘5’ or ‘8’ as the second last digit means it has 1866MHz memory support. This is mainly to benefit the inbuilt higher end GT3 Iris 6100 or HD 6000 GPUs giving the necessary bandwidth to sufficiently feed them, which was shown to be very effective with the 4th generation parts too.
The lowest, GT1 HD Graphics found on the Pentium and Celeron versions are actually the same die as the GT2 HD 5500 parts but have half of the EUs disabled, to recover yields from manufacturing defects in the GPU areas.
4K AND WIRELESS
Feature wise, Broadwell’s GT3 and GT2 powered products now support 4K resolutions at 60Hz compared to the previous 30Hz and also support 4K H.265 decoding (though not purely hardware accelerated) at 30fps. Broadwell GT1 powered products now also sport two features previously reserved for the GT3/2 products, Quick Sync (which is now also up to 2x faster) and Wireless Display support. Improved API support with DirectX 11.2 (DX12 too when it comes) and OpenCL 2.0 round out the improvements.
DOWN SOUTH
The smaller chip on the CPU package (the top die in the top-left image), the Platform Controller Hub (PCH) or Southbridge to those that have been around a while has had two improvements made to it. The first more minor one is some improved I/O throttling, power and thermal management for better battery life and allows for the ‘wake on voice’ ability.
That’s right, with Broadwell-U you will be able to say “Hello HAL” (or whatever you like) to bring your laptop out of sleep without touching it!
AUDIO TRICKS
The second and larger improvement on the PCH, Intel are integrating their DSP (Digital Signal Processor) right into the PCH removing some extra, typically Realtek, components from the system and allowing for better and quicker power gating for even more power savings. The beefier DSP now also allows for Waves and DTS post processing and enables hardware accelerated real time voice recognition, likely making that feature a big selling point on systems this year, a certainty with Cortana (think Siri) coming with Microsoft’s upcoming Windows 10. Dictating emails and commanding your PC to play a specific song or to Google something without touching your PC could be about to happen.
THE FUTURE
Broadwell won’t be coming to replace budget socketed desktop Haswell parts, though performance and HEDT parts should get the Broadwell treatment by mid-2015 as well. When it does come though it will see for the first time Iris graphics coming to socketed systems, which could give reason for AMD to worry, IGP graphics is its strongest and only niche it can compete well in at the moment.
Due to the initial 14nm production ramp up issues Broadwell is being rolled out quite late. By the time the new high end laptop Broadwell-H and desktop Broadwell-K parts come, Skylake (the next architectural refresh) will be just about ready to launch in the second half of 2015, giving mere months for some Broadwell parts before they potentially become outdated.
The 14nm process should be a lot more mature by then though and should see Skylake’s release not be quite as lengthy as Broadwell’s has been.