For much of the past year we've been hearing that Intel's Atom for Windows 8 tablets is going to be the one to beat. Ivy Bridge (and later, Haswell) will exist at the high-end of the Windows 8 tablet space but if you want Intel's answer to ARM based Windows RT tablets it's going to come from the Atom lineup. It's still too early to talk about pricing, but expect Atom based Windows 8 tablets to exist in the sub-$600 space. Exactly how low they go will depend entirely on what the OEMs decide to ship at. My hope is for prices to start around $399 rather than much higher but we'll see just how seriously the Windows 8 OEMs are going to take this launch.

Intel's Atom for Windows 8 tablets has gone under the codename Clovertrail for quite some time. Today it gets official: the first Clovertrail SoC is Intel's Atom Z2760. Following similar naming to Medfield's Atom Z2460, there's a lot more that's shared between Clovertrail and its smartphone counterpart.

Similar to its approach with Medfield, Intel built a Windows 8/Clovertrail form factor reference design. The 8mm thick 10.1-inch tablet was built by a single ODM, but four manufacturers total are allowed to reuse those designs as they see fit. The FFRD approach isn't as necessary here as it was with Medfield because most of the traditional PC OEMs are already used to working with Intel. Given Intel's intense focus on driving platform power down however, building a reference design that others can follow makes a lot of sense. We'll actually see even more of this with Haswell next year.

From an availability standpoint we'll see the first Atom based Windows 8 tablets this fall. Intel announced design wins with Acer, ASUS, Dell, Fujitsu, HP, Lenovo, LG, Samsung and ZTE. The thinnest tablets will measure 8.5mm in thickness and weigh as little as 1.5 lbs. Not all Atom based Windows 8 tablets will be available on October 26th, but we'll see them starting a few weeks later.

Atom's big promise of course is ARM based tablet pricing with full x86 backwards compatibility, allowing the use of virtually all of your existing legacy Windows 7. It's a pretty compelling sell. If Intel can deliver the same (or better) performance/battery life compared to the ARM based Windows RT tablets, while preserving backwards compatibility Clovertrail would seem like a no-brainer. Simple solutions are rarely so simple, so we'll have to see this one play out in the market to be sure. Until then, we have some much needed architectural detail on Clovertrail and the Atom Z2760.

The Architecture

Medfield vs. Clovertrail
  Intel Atom Z2460 Intel Atom Z2760
Platform Codename Medfield Clovertrail
OS/Platform Target Android Smartphones Windows 8 Tablets
Manufacturing Process 32nm SoC (P1269) 32nm SoC (P1269)
CPU Cores/Threads 1 / 2 2 / 4
CPU Clock up to 2.0GHz up to 1.8GHz
GPU PowerVR SGX 540 PowerVR SGX 545
GPU Clock 400MHz 533MHz
Memory Interface 2 x 32-bit LPDDR2 2 x 32-bit LPDDR2

Clovertrail is the platform name, the single-chip SoC is called Cloverview. The architecture is very similar to Medfield's Penwell SoC. The most obvious differences are in the CPU and GPU configuration. Cloverview features two 32nm Saltwell Atom cores instead of one in Medfield/Penwell. These two cores run at up to 1.8GHz, a slightly lower clock speed compared to the Penwell that ships in Motorola's RAZR i. Each core has its own private 512KB L2 cache.

The GPU is a PowerVR SGX 545 from Imagination Technologies, clocked at a very high 533MHz. Direct3D feature level 9_3 is officially supported. Intel claims that the GPU is fed by a better engine in Clovertrail/Cloverview than it is in Medfield, however any additional details were impossible to come by.

The memory controller remains a dual-channel LPDDR2-800 design. Most tablets will see two 1GB devices populating the channels. Package on package (PoP) stacks will be used for DRAM and SoC integration, similar to what you see in a smartphone.

The other changes are more subtle. Video encode/decode is handled by IP licensed from Imagination Technologies, however the encoder is newer than what was used in Medfield. Clovertrail uses the same Silicon Hive ISP from Medfield. It supports two cameras (2MP/8MP) and burst mode.

The platform supports true connected standby, meaning Intel's new S0ix sleep states (similar to what was announced in Haswell). I realized I haven't yet detailed what these mean yet but in short on DC power you can expect polling roughly every 30 seconds for new data (incoming emails, tweets, etc...) delivering an experience somewhat similar to a smartphone. Off-SoC device drivers need to support Windows 8 run time power management (RTPM) to support these new low power sleep states. Intel claims that in its lowest platform sleep state (S0i3) the SoC's power consumption is below 2mW.

Connected standby is only currently supported by 32-bit Windows 8, so although Clovertrail supports x86-64 the platform will launch as 32-bit only. There's no support for alternate OSes at this point.

The SoC doesn't support SATA, just eMMC like most other smartphone/tablet SoCs. This is a bit of a disappointment as most eMMC controllers are pretty bad, but Intel tells us they've been working to improve things with the controllers that are out there.

There's no USB 3.0 support, Clovertrail just supports two USB 2.0 ports (OTG + xHCI, although OTG isn't supported by Windows 8). OEMs can obviously integrate hubs in any docking stations they may build.

On Pricing and ARM

Intel claims that there's no reason that Atom based Windows 8 tablets, from a hardware bill of materials perspective, should be any more expensive than their ARM based counterparts. The important takeaway is that Intel is significantly reducing the price of the Atom Z2760 due to competitive pressure from ARM. Most ARM smartphone SoCs seem to be priced in the $15 - $30 range, and I'd expect the Z2760 to fall somewhere in that range. Intel has shipped cheap CPUs in the past, but I don't know that they've ever shipped something this cheap. ARM's impact on Intel is measurable, it is the new AMD.

On Performance and Power

Microsoft isn't allowing any hands on performance of Windows 8/RT tablets yet so we don't have any of our own performance data to share. Intel did share some SPEC CPU2000 data it ran on its own with competing platforms. The data below wasn't generated by us so take it with a gigantic grain of salt:

Intel Generated SPEC CPU2000 Comparison - Normalized to Snapdragon S4
  SPECint SPECint_rate
Qualcomm Snapdragon S4 (1.5GHz) 1.00 1.00
Dual-Core 40nm ARM Cortex A9 (1.8GHz) 1.14 1.14
NVIDIA Tegra 3 (1.3GHz) 0.86 1.25
Intel Atom Z2760 (1.8GHz) 1.20 1.54

Everything here is normalized to the performance of Qualcomm's Snapdragon S4 (dual-core Krait, 1.5GHz). Basically it shows a tangible advantage for Clovertrail. That's not too hard to believe given what we've seen in the phone space, although we'll have to wait and see once we get our hands on final hardware. Sunspider scores at or below 800ms should be possible as that's what we've seen on preproduction hardware already.

We've already established that Medfield is competitive from a power standpoint with ARM based SoCs. It doesn't offer the best power characteristics, but it's hardly the worst. Middle of the road is the best way to put it. We don't have (and aren't allowed to have) a Clovertrail based Windows 8 tablet yet, so we'll have to reserve full analysis until then. However, Intel did share some early data with us from its own testing that points to Clovertrail battery life being competitive with other platforms:

Intel Generated Power Consumption Comparison
  Idle (Screen On) Web Browsing HD Video Playback
ASUS Transformer Pad Infinity 2.7W 3.4W 3.1W
Apple iPad 2 2.5W 2.6W 2.5W
Apple iPad (2012) 4.3W 4.5W 5.9W
Intel Clovertrail FFRD 2.3W 2.8W 3.0W

Intel standardized on 200 nits for all of its battery life tests, however I wasn't allowed to study/mirror the workloads and test procedure. The data looks good for Intel. Clovertrail's power consumption appears to be lower than NVIDIA's Tegra 3 and a little worse than Apple's iPad 2. This all looks quite plausible, I'm curious to see how power consumption would compare in Intel's tests to Qualcomm's S4. We'll find out for ourselves in due time.

Final Words

Intel was pretty light on Clovertrail details other than what we've published here. The real work begins once we start getting hardware late next month. The biggest question is really whether or not the OEMs will get pricing right for these tablets. An affordably priced Windows 8 tablet running Clovertrail can be very compelling for someone looking to carry a single device instead of a tablet + notebook. As with most things however, I am worried that we'll have to wait at least one more generation for perfection. I can't tell if I'm being cynical or realistic. Let's hope I'm surprised come October 26th.



View All Comments

  • Penti - Friday, September 28, 2012 - link

    The New iPad (iPad 3-gen) uses a 42Wh battery which is actually a larger battery then MacBook Air 11.6. Android tablets tend to use less power consumings SoC's and displays so they do fine on 20-30Wh. Down to about 15Wh. As does x86 Atom stuff when Ivy Bridge does fine on 35Wh (MBAir11). Current atom-powered Tablets PC's like HP Slate 2 or Dell Latitude ST uses a 30Wh battery and they are way more power consuming then these chips. Granted though that those are only good for 6 hours but are more power hungry. They don't need a 60Wh battery here to achieve 10 hours, not 50Wh either. iPad 2 uses a 25 Wh battery. With it's 1024x768 resolution.

    Z2760 is a 1.7W chip rather then a 3.75W platform though. Max TDP estimates of course. If you save just 2W every hour that is still 10 Wh for a 5 hour usage period. It's still mostly WLAN, Display, WWAN etc that uses power in these devices.

    Semiaccurate article is ridiculous for several reasons first there is no Office 2013 RT yet, there is no Outlook for WOA/Windows RT. There won't ever be any Outlook or Microsoft powered Enterprise email client for Windows RT. They are devices and are managed way worse then even iOS and Android tablets are. Then again their competition aren't Android and iOS tablets, and Atom computers is an full feature computer. It's managed by IT as a computer, it's not competing against Windows RT devices and it can run Office today where there is none available for Windows RT at release. Plenty of ARM SoC's use more silicon then the Intel Clovertrail in mobile variants. That it is designed for Microsoft is moot when ARM-powered Windows RT devices will be just as locked down if not more. It's not like you can virtualize another OS on the ARM-devices either. Drives for PowerVR on Windows RT won't exactly be any better either it's still WDDM drivers. What this chip competes against is Brazos 2.0 and Hondo APU's and coming Temash/Kabini APU's from AMD. Temash will have GCN-graphics but Intel's alternative will be on their own Intel graphics by around then. Besides Atom Z2580 is capable of running Android. If that is your gripe.

    Z2760 is already pretty much out in products today, reviews of pre-production stuff is already around. Availability is 26 October. I.e. Windows 8 release. They are fully competitive against early Windows RT ARM-tablets. Even battery wise. They do run Office 2010/2013 beta, where you have nothing for Windows RT today. If you look at Surface RT vs Pro battery, RT will have a 31.5Wh battery and Pro will have a 42Wh battery, but that is a Ivy Bridge powered device! A Samsung Galaxy Note 10.1 uses a 25.9Wh battery. The Galaxy Note 10.1 battery weights 136 grams. It's still much smaller then the 42.5Wh battery of iPad 3-gen. No real issue here. How is that more then twice as large? iPad is a 9.7-inch device. Note 10.1 is of course a 10.1-inch. It's roughly twice as large as a 7/7.7-inch device but much of that comes form the display! It's note twice as large as Note 10.1 or Tab 2 10.1 with the same 25.9 Wh battery for Tab 2. Add 25-30 g and you fit the slightly larger battery in there.

    PowerVR Series 6/Rogue aren't out in ARM-SoC's yet either, but Intel's own GPU technology does support Windows/DX/OGL fairly well compared to PowerVR-Windows drives. When you get Valleyview next year with Intel graphics, it should work pretty well as a computing platform. After Saltwell based stuff you also get Silvermont (like Valleyview). It's not like Z2760 are suppose to compete against the competition in a years time, late 2013. It's not a new generation chip it's still 2008 Atom-architecture/pipeline. Z2760 is only aimed at tablets where 1.7W TDP is actually okay. Android stuff can always use Z2460, Z2560 when available or use whatever else Hondo aren't meant to run it but you can always make it run, should compete well with Windows-based devices though.

    Intel's reference platform here on Z2760 uses a 30 Wh battery just read the damn press release, it's video playback with WiFi activated, but local playback. Over 10 hours for that scenario is totally reasonable. The only real difference on this platform against full featured notebook chips is that it will run 32-bit Windows rather then 64-bit. The platform will use about the same size batteries as ARM-based Windows RT devices. But for summary i.e. 25Wh iPad 2 is not significantly smaller then a 30Wh battery Z2760 device.
  • relic1138 - Tuesday, October 16, 2012 - link

    I will bet anything that this CPU will get you a max of 6 hours of battery life when it's first introduced. I have never seen a 10 plus hour Atom system, real world not paper specs. My Samsung 7.7 Tab, now that get's 12 hours consistently. Reply
  • Ailuros - Saturday, September 29, 2012 - link

    SGX545 belongs to the Series5 family as ltcommanderdata already noted and therefore has four Vec2 ALUs, a quite strong triangle setup unit and 16 z/stencil units. Series5 is not configurable in multiple cores, it's just one core in Cedartrail/Clovertrail clocked at 533MHz.

    Apple's GPUs since the iPad2 have Series5XT GPUs which can scale multiple cores and the SGX543MP3 in A6 should have a frequency of 300MHz at least.

    In terms of triangle throughput a SGX545@533MHz vs. a SGX543MP3@300MHz should be on comparable levels, the MP3 has almost 60% more texel fillrate, about 70% higher z/stencil/pixel fillrates and >120% more ALU throughput.

    Frequency by itself doesn't define final performance. As for Clovertrail Intel stated DX9.1 there (whatever that means...probably DX9.0L3) and OpenGL3.0. OGL3.0 is far and beyond above DX9L3 capabilities so it's probably just an issue with IMG getting WHQL certification for DX10.1 for Cedartrail initially and now probably also for Clovertrail.

    Other than that Apple's SGX543 GPU cores are just DX9.0, while SGX544 is DX9.0L3, but under iOS anything above DX9 seems to be redundant for the time being. A windows platform is an entirely different chapter.
  • fteoath64 - Monday, October 1, 2012 - link

    Good estimation on the the gpu performances. We shall see soon when the benchmarks are released on an equal (as close as possible) footing. The good news for Intel is that the power consumption of this chip is respectable but clock for clock, it is almost on par with Tegra3 and considering Tegra 3 has only a single channel memory and a 12 pipeline gpu. The next iteration of Tegra3 will be significant. Even if Nvidia choose to release a slightly tweaked Tegra 3.5 (eg dual ch LPDDR3 1333Mhz, 16pipe Geforce update (400mhz --> 600mhz turbo core) and cpu cranked to 1.8Ghz. This will step the Tegra another 30% ahead of this atom!. Also Intel with their cheapo 32nm process where it could very well do 22nm runs since this is going to be small volumes due to very few customers ....
    Almost there but the competition just went another step or two further.

    Does it look like Intel is intending to "lock" ARM out of the low-end of the Win8 tablet market ?. If they later slash prices aggressively, it might just work for them. But the issue is that Android is relevant and will keep up its momentum in the tablet space for a long time to come. Win8 RT might see a limited run due to high prices!. That would be a shame.
  • Wilco1 - Monday, October 1, 2012 - link

    There are indications that Win8 tablets will cost much more than WinRT ones despite WinRT having faster CPU/GPUs, lower power consumption and likely better resolution screens. Win8 makes sense if you absolutely need x86 compatibility and are willing to pay more. That would make Win8 popular with businesses and WinRT with the general public.

    So on the consumer side I predict the battle will be solely between Android, iOS and WinRT tablets. Businesses are likely to go with Win8 by default.
  • relic1138 - Tuesday, October 16, 2012 - link

    No indications they will cost more, Samsung and Asus in Europe have both posted pre-order pages for their tablets running this CPU. They start at 600 without keyboard and 700 with, this is for the bottom configs. Reply
  • thebeastie - Tuesday, October 9, 2012 - link

    I just cant help but think about the fact that if I am in a Windows ARM RT environment any anti-virus scanner I have wont need to look for like 1 million+ viruses since they cant run x86.. Just makes me feel a lot better.

    I think the only fair benchmarks you can run is an Clover Trail Atom Win 8 tablet WITH active AV going in the background VS a Windows RT tablet.
    Cant help but think that the Clover Trail will need all the extra grunt it can muster to hold onto some performance, and it better be doing that AV protection with out sucking the battery, yeah good luck with that.

    Anyway will see in the benchmarks, oh yeah its not going to be benchmarked to satisfy the average user setup with active AV installed is it?
  • Wolfpup - Friday, October 26, 2012 - link

    I'm impressed that Intel really seems to have gotten a just plain better product here...looks like they're beating performance, matching or beating power, and of course most importantly...this can run real Windows, your real programs, etc.

    Very cool, but I have to wonder, what about AMD's c and e series CPUs?

    Are they still manufactured at 40nm? Do they not support this new polling stuff? If not, then I guess this Atom would make more sense...but I'd still feel better about having an actually-kinda-modern-ish dual core 1.6GHz (or whatever) e chip from AMD...or of course an A series chip would be ideal, since you can actually plausibly use an A8 or A10 as your main PC, even for games...

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