Mark
Hachman Senior Editor As PCWorld's senior staff writer, Mark focuses on
Microsoft news and chip technology, among other beats. He has formerly
written for PCMag, BYTE, Slashdot, eWEEK, and ReadWrite. More by Mark
Hachman
Take a deep dive into Skylake's 48 new CPUs, from energy-sipping mobile versions to beefy overclockers.
Trying to figure out which sixth-generation Intel Core chip to buy in
Intel’s Skylake family is like going to a preseason baseball or football
game. There are numbers everywhere. Somewhere in the crowd are the
superstars. But which ones?
Here’s what you need to know about Skylake in a nutshell: The prices
that Intel has published appear to essentially to be the same that Intel
is charging for its Broadwell chips—meaning that, from a price
perspective, it’s a no-brainer to bypass Broadwell or Haswell for
Skylake. But there’s a catch for desktop users: Skylake uses a new
motherboard socket and memory, meaning that you’ll practically have to
invest wholesale in a new system.
For laptop users Skylake does hit a new, lower, power threshold, so your
portable’s battery should theoretically last a bit longer.
Intel announced five families of microprocessors at IFA: four for the
Core family, as well as new Core m (yes, lowercase 'm') designations for
the i3, i5, and i7. If you’re buying an Intel-based tablet, chances are
it will include a Core Y-series chip. Thin-and-light notebooks will use
the U-series chips. So-called “ultimate mobile” systems and performance
workstations will include the H-series chips, while the S-series chips
will be included in both performance and value desktops, all-in-ones,
and mini PCs.
A quick guide to the charts
We’ve included Intel’s processor charts throughout this story. Just like
baseball statistics have evolved from batting average and ERA to WAR
and OPS+, so have the metrics Intel uses to describe its processors.
Price, clock speed and the number of cores still remain as the primary
metrics. Just note that the price Intel is quoting are for a bulk order
in lots of 1,000. You’ll typically pay more for an individual chip
initially.
(And while this may sound obvious, here’s a handy tip: Almost all
6th-generation Core chips—aka the “Skylake” family—use a '6' as the
first number of their product name, such as the i5-6500T.)
Modern operating systems like Windows 10 are better at divvying up tasks
among the multiple cores that most processors include, so a greater
number of cores and threads generally translates into improved
performance. If necessary, those cores can kick into “turbo mode,”
temporarily overclocking themselves to complete a task quickly. Core i3
chips lack this capability.
Consumers shouldn’t have to worry about Intel’s Stable Image Platform
(SIPP) or Small Business Advantage (SBA) technologies. Ditto for Intel
vPro. You might want to consider buying a chip with Intel TXT technology
built in, however; that’s the Trusted eXecution Environment which seems
to be at the heart of new Windows technologies such as Windows Hello
and Passport. Virtually all of the new Skylake chips include
virtualization technology—a geeky way to test out a future version of
Windows 10, but essential if you want to run Android apps on your PC.
Note: Not everything Intel is announcing today will be
immediately available. (If the price is listed as "To Be Determined,"
(TBD) Intel will ship it at a later date -- either during the fourth
quarter or in early 2016.)
High-end desktops: the S series
While Intel hasn’t announced any of its high-end “Extreme Edition” parts
yet, the first thing that should strike you is the overall reduction in
power, although it may not seem apparent initially.
An Intel 4GHz Core
i7-4790K Haswell CPU, for example, is rated to dissipate 88 watts of
heat. Its direct replacement is the 4GHz Core i7-6700K, which has a
“TDP” rating of 91 watts. Both of these CPUs are designed for
enthusiasts who will overclock.
The better comparison would be the 3.6GHz Core i7-4790 chip that doesn’t
overclock. Even with its lower clock speeds, it maintains the same TDP
rating of 84 watts. For Skylake, the 3.4GHz Core i7-6700 that can’t be
overclocked has a TDP rating of 65 watts. To be fair to Haswell, there
was a Core i7-4790S version with the same TDP rating as its Skylake
counterpart, but the clocks drop even lower, to 3.2GHz.
Even though Skylake
represents a processor redesign and not a process shrink—where most of
the power reduction takes place—Skylake should consume less power than a
similar Haswell chip.
The other thing to notice is that, at least for now, all of the desktop
chips that Intel has announced have at most four cores and eight
threads. Intel’s Core i7-5820K and higher “Haswell-E” chips that use
larger sockets and don’t contain integrated graphics all contain 6 cores
and 12 threads. It’s not clear whether Intel plans to add similar parts
in the future, or leave a 4-core/8-thread as the high end in the
smaller socket.
What does seem clear, though, is that are only single Core i5 and Core
i7 unlocked “K” versions of the Skylake parts; it’s virtually assured
that more will be added over time.
From a graphics perspective, the desktop chips are virtually identical:
They all use the new Intel HD Graphics 530 core. Just be aware that some
of the slower chips—the i5-6400, specifically—have their graphics cores
clocked lower under load. Still to come are Intel’s Skylake chips using
embedded DRAM, which should greatly increase graphics performance.
The desktop Pentium chips
Intel resuscitated the Pentium brand awhile back, a seemingly odd
throwback to the days not too long past when gamers had to tweak
HIMEM.SYS and other system files to allow their PCs to work. Today, an
Intel Pentium is synonymous with low cost. Intel will also launch
Celeron versions of Skylake in the future, at an even cheaper price.
You can see that buying a Pentium isn’t that bad of a deal for basic
computing. Here’s the interesting thing, though: Because there’s no
Turbo Boost self-overclocking mode, the Pentiums are actually clocked faster
than some of their Core cousins. Couple that with a pared-down cache to
save cost, and the result is a cheap chip that’s going to run at full
speed fairly aggressively. The only caveat is the lack of
Hyper-Threading, which is Intel’s virtual CPU technology that makes two
CPU cores act like four. Depending on what you do though, you may not
feel it.
And no, cheap gamers, we asked: Intel said none of the new Skylake
Pentiums support overclocking, like it did with the “Anniversary
Edition” Pentium G3258.
Intel’s mobile Skylakes include Xeon, overclocking
Intel can’t shave as much power in the mobile space, where the maximum
thermal power of a Broadwell chip, 47 watts, is nearly identical to the
45 watts that a mobile Skylake processor consumes. Here, though, Intel
is focusing on the time in which the chip needs to be powered
up. Intel’s Skylake-specific Speed Shift feature reduces the time in
which a chip needs to shift from a high-power to a low-power sleep state
to as little as 1ms, versus 30ms or so before. This sounds like a tiny
detail, but when the chip is constantly shifting from a full-power
“busy” state to a sleep state, it’s a big deal.
One of the oddities of the new mobile Skylake line is the new mobile
Xeon "server" processor, designed for true mobile workstations. Intel
has already begun shipping the chip—at the SigGRAPH show in August,
Lenovo announced the P50 and P70 workstations, including the chip as well as peripheral enhancements like Thunderbolt 3.0, based on the new Intel Alpine Ridge controller.
Gamers, though, may want to think about the Core i7-6820HK. Why? Because
it carries that magical “K” suffix, meaning that it’s overclockable.
Yes, an overclockable mobile chip! At IDF, Intel executives said we’d be
seeing laptops with an easy-peasy, one-touch overclocking mode by way
of a 'turbo' button. It’s possible that some might be shown off at the IFA show this week. We’ll keep our eyes out.
In general, though, Intel’s mobile chips show a definite progression
down the performance curve: The more expensive Core i7s boast larger
cache, robust Turbo Modes, and a faster maximum graphics clock speed.
All of these factors decline as the processors step down into the Core
i5 and Core i3 range.
Be aware that Intel also has two other lineups of Core i7/i5/i3 for
ultrabook PCs consuming 28 and 15 watts. In general, you should expect
lower performance but longer battery life with these chips. Because
laptops in general are getting thinner by the day, it might not be
totally clear whether you’re buying an 'ultrabook' or just a thin
laptop.
These lower-power chips differ from the more robust 45-watt variants in
two key ways: The number of cores are significantly reduced. Also, Intel
has included what appears to be a down-clocked mode, for activities
like simply displaying this article, for example, that require less
exertion from a chip.
You’ll also notice two graphics variations: a slightly underclocked
version of the HD Graphics included on the 45-watt chips, as well as an
entirely different Iris Graphics architecture. The Iris Graphics brand
has generally been used for Intel’s premium graphics product, which
means the lower-power products may actually outperform the chips with
more cores. (But note the "TBD" designation in the pricing column. Iris
Graphics is coming later, and Intel's not saying when.)
If you’re wondering why, it’s likely because higher-wattage quad-cores
are almost always coupled with discrete graphics for more performance.
The lower-power U-series chips almost always go it alone with integrated
graphics. Still to come will be the Iris Pro version, using
its own dedicated 64MB or 128MB eDRAM frame buffer.
One has to wonder whether, over time, Intel might add a 4-core/8-thread
version of the 28W Core i7 chip, as a middle ground for gamers.
Eventually, the PCI-SIG hopes to mainstream a technology called Oculink, which lets gamers could tote around a low-power laptop by day and connect it to an external GPU for gaming after hours.
The Core M (sorry, Core m) now has its own naming scheme
So-called two-in-one or hybrid devices occupy their own little niche:
Sometimes they’re a tablet, and sometimes they’re a notebook. Now, with
Intel’s new Skylake Core m chips, you’ll have a better sense of what’s
what.
What surprises me most, however, is the price Intel’s charging—almost
$300 a pop in most cases. That means the Skylake Core m definitely won’t
be appearing in devices that will compete with Android tablets. For the
price of a Core m, you’d be able to buy a decent Android tablet all by
itself.
The Core m, however, features both upclocked and downclocked modes,
allowing the tablet to rev up when needed, then clock down when not.
(The Core m3 can also enter Turbo Mode, unlike the Core i3.)
While the Intel HD Graphics 515 chip is part of the Skylake family, it’s
pretty bare-bones in terms of performance. Still, the selling point is
power: Core m chips run at just 4.5 watts, and Intel believes you’ll get
up to ten hours of battery life with a Core m tablet.
Know your chips to make the best purchase
If you’ve read this far, you should have a better idea of what
distinguishes which Intel Skylake chip from another. It's useful
information, because eventually, you’re going to see an ad or a sign
advertising a “Core i7” computer on heavy discount, and you’re going to
be tempted. You should be able to figure out whether the vendor is
selling an older Broadwell chip, or perhaps a low-end Core i3 that isn’t
what you’ll want.
Remember, too, that Intel’s Skylake is more than just a chip—it’s also a
collection of technologies designed to revamp the PC. To learn more
about those, see our overview of Intel’s Skylake.
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