Intel Skylake laptop CPUs should use less power, run faster, and can even drive three 4K monitors

18.08.2015
After weeks of teasing us, Intel finally lifted the kilt to show us details of its 6th generation CPU. Besides being faster and using less power than its predecessors, Skylake chips can drive multiple 4K displays, feature new instructions to speed up security operations, and even hardened memory defenses.

But those expecting the full monty on how much the chips will cost, how many cores they’ll have, and when you can buy a laptop with them will continue to be disappointed.

“Today is not the launch of Skylake,” Julius Mandelblat, an Intel senior principle engineer said to a frustrated room of developers, hardware vendors and engineers who peppered him with specific product questions after his presentation about Skylake. That news, Intel officials said, won’t come for another “couple of weeks.”

Still, Intel’s disclosures point to a processor worthy of the wait. Let’s cover the highlights:

New to Skylake is a feature called Speed Shift which is a power-saving technique that lets the CPU intelligently change its power state. Intel’s power clock savings technique is fairly rigid today, but Speed Shift in Skylake laptops should improve responsiveneswhen coming out of a low power mode (compared to a Broadwell or Haswell CPU) as well as more performance when in a low power state. Speed Shift is just one of the power saving modes Skylake implements, but it’s probably the coolest sounding.

Intel didn’t specifically say how much of an increase in battery life Skylake would offer over its 5th gen Broadwell chips. PC OEM’s I’ve spoken to said it’s a good improvement, but don't expect that major leap we saw going from Ivy Bridge to Haswell.

The CPU core itself is more efficient and able to handle more instructions simultaneously than Haswell or Broadwell CPUs could. 

Another secret weapon of Skylake will be the new memory subsystem. Intel has been embedding chunks of DRAM into the CPU package since the Haswell days to help improve memory bandwidth for gaming.

With Skylake CPUs it’s been upgraded to something Intel calls “eDRAM+.” It continues to act as a cache to store recently used data and instructions but it’s now fully coherent, which means it can be used to cache information for the CPU, not just the GPU. That should add up to increased performance in things other than just gaming.

That eDRAM on Skylake will also see far wider use. With Haswell and Skylake, eDRAM was limited to one or two chips with 128MB of eDRAM. With Skylake, the eDRAM can now be sized to either 64MB or 128MB and be made available in far more laptops.

On desktops, Skylake’s performance improvement was decent but didn’t match the hyped leaks. On laptops, there’s a good chance Skylake will surprise us more as the power savings can sometimes be turned into performance improvements.

With security on everyone’s mind, Intel is introducing two new extensions aimed at locking down the PC. The first is Intel’s SGX or Software Guard eXtensions. SGX is aimed at reducing privileged attacks by malware in a system. SGX works hand in hand with Intel’s Memory Protection eXtensions which are also designed to build isolated sections of memory. Whether this would protect against “row-hammering attacks” but it’s possible this could help.

It’s no secret that Intel’s been putting a lot more emphasis on integrated graphics over these last few generations and one slide at IDF drives the point home. If you think of a CPU’s die as valuable real-estate in Manhattan, we’ve gone from it taking up a small sliver in the 2nd gen Sandy Bridge chip to accounting for almost half of the CPU area.It’s here where Skylake gets the most improvements. While Haswell could drive a 4K monitor at only 30Hz, and Broadwell could drive a single 4K monitor at 60Hz, Skylake is capable of driving three panels at 4K resolution and 60Hz.

Intel has also integrated fixed-function support of 4K video processing in hardware. That means Intel has dedicated transistors directly to the job of decoding and encoding 4K. In one demonstration showing playback of a 4K RAW video stream from a Canon video camera, playback was smooth using the Skylake graphics chip, while using just the CPU, it would constantly drop frames.

That same 2nd-gen Sandy Bridge chip had a peak shader GFLOPS performance of 130 GFLOPS, Intel said. Intel’s Skylake graphics can exceed, 1,100 GFLOPS. Skylake graphics improvement, in fact, impressed me on the desktop chip and I’m looking forward to seeing it in a laptop.

All told, Skylake looks like it will be solid improvement over Broadwell when it comes in laptops and mini NUC-style machines, but the question is when. With various engineers throwing out “two weeks” as a launch date, that puts it right around the start of the IFA trade show in Berlin.

(www.pcworld.com)

Gordon Mah Ung

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