Thickness, Thermals and Core: Understanding how Surface Pro 3 Got so Thin

Ever since Surface RT showed up I've wanted Surface Pro but in the RT chassis. Microsoft seemed to consciously avoid any lower TDP Core processors in favor of Ultrabook SKUs, which pretty much kept Surface Pro thicker than its ARM-based counterpart. Surface Pro 3 changes everything with a rethinking of how Microsoft embraced the thermal constraints of a tablet.

Surface Pro 3 is available with one of three CPU options: a Core i3, Core i5 or Core i7. The latter two are 15W TDP parts, while the former is a 11.5W TDP/6W SDP Haswell Y SKU. Haswell Y is really designed for passively cooled form factors, but all three CPU options receive the same heatpipe and fan cooling system offered by the Surface Pro 3. In short, the Core i3 model should behave a lot more like a standard Ultrabook part (sans Turbo).


Surface Pro 2 (left) vs. Surface Pro 3 (right)


Apple iPad Air (left) vs. Surface Pro 3 (right)

Microsoft's claim to fame is the ability to build the world's thinnest device with a Core series CPU inside. At 9.1mm thick, the Surface Pro 3 is just barely thicker than last year's Surface 2 but with a full blown dual-core Haswell instead instead of a high-end phone/tablet ARM SoC. As both the Surface Pro 2 and Surface Pro 3 used 15W Haswell Ultrabook parts and Microsoft claims a performance increase over last year's model, the question is how Microsoft can reduce thickness, keep TDP the same and increase performance. The answer is simply a difference in what's acceptable from a thermal standpoint.

Here's a look at the original Surface Pro while running an hour long loop of 3DMark Ice Storm Unlimited. I chose this test in particular as it behaves as a nice balance between CPU and GPU workloads on the device:

You can almost trace out the path of the heat pipe carrying the thermal load away from the CPU and to the two fans in the system. I measured peak temperature here at 41.7C.
Now let's look at Surface Pro 2:

Despite a move to Haswell, Microsoft lets the device get much warmer. You can make out the same U-shape thermal distribution as heat is carried away using the two fans, but the temperatures are much higher. I measured a maximum temperature running the same workload of 47.3C.

Here we have Surface Pro 3:

Right away you can see the new cooling system at work. The thermal load is mostly confined to the left side of the image (we are looking at the back with the kickstand unfolded towards the camera, so if you were looking at the display we're talking about the upper right side of the machine). The cooling solution is far more compact and I suspect ready for a move to Core M (Broadwell). Peak temps however are much closer to Surface Pro 1 at 43.2C.

The thermal story points us in the right direction. Either Surface Pro 3's fan and heatpipe configuration is able to remove heat far better than Surface Pro 2's design could, or the CPU in SP2 doesn't get as warm. I suspect it's the latter.

For starters, I'm guessing that Intel is helping Microsoft with delivering better binned Haswell ULT and Y series SKUs. But the big change is I believe Microsoft is more aggressive about reducing CPU and GPU frequencies in Surface Pro 3 compared to Surface Pro 2. Benchmarks will show an increase in performance due to more aggressive ramping up/down of clock speeds vs. Surface Pro 2, but prolonged load cases will likely show a decrease in performance vs. last year's model.

I first stumbled upon this behavior while trying to gather thermal data for Surface Pro 3. I noticed large run to run variance if I repeatedly ran 3DMark 11. I'm used to seeing this sort of behavior on smartphones that throttle quickly, but it was unique for a Surface Pro device.

3DMark is a synthetic test so the real question was how would Surface Pro 3 perform in a real world scenario where sustained CPU/GPU load was guaranteed for a long period of time. I figured a game playable on the machine like Dota 2 would be a great example. I asked our own Ryan Smith to whip up a custom benchmark using the game and I ran it on Surface Pro 1, 2, 3 as well as a 13-inch MacBook Air (Early 2014). The graph below illustrates average frame rate during our Dota 2 benchmark for all of the systems:
As you can see, even with Surface Pro 3's fan running the platform doesn't deliver sustained performance equal to last year's model. It's an understandable tradeoff given the substantial reduction in device thickness (and thus improvement in usability), but it's important to note nonetheless.

Dota 2 Performance - ATDotaBench

Workloads that are CPU and GPU heavy are one thing, but what about sustained productivity workloads? Penny Arcade's insanely talented artist Gabe mentioned that he noticed substantial lag when drawing on his Surface Pro 3. As Surface Pro 3's NTrig pen is actually lower latency than Surface Pro 2's, I wonder if what Gabe ran into might be thermal related rather than pen related (alternatively it could have to do with the much higher display resolution that Surface Pro 3 runs at). I needed a repeatable workload to see if non-gaming use cases also showed a regression. Thankfully PCMark 8 v2 provides a number of relatively long, repeatable workloads that are great for testing just this.

I decided to use the PCMark 8 v2 Work suite which includes web browsing, office producitivity (word processing and spreadsheet work) and video chat. It's a far cry from a Cinebench loop but I figured if I saw throttling here it would easily be present in heavier workloads. Each run of the suite actually repeats the tests three times and takes around 20 minutes to complete on the Surface devices. I measured performance for three suite runs (9 total runs of the Work loop) on both Surface Pro 2 and 3:

PCMark 8 v2 Work Performance Over Time
  Work Suite Run #1 Work Suite Run #2 Work Suite Run #3
Microsoft Surface Pro 3 (Core i5) 3273 3031 (92% of peak) 3129 (95% of peak)
Microsoft Surface Pro 2 (Core i5) 3222 3223 3218

As you can see, there's a 9% drop in performance on Surface Pro 3 from the first suite run to the next while Surface Pro 2 delivers consistent performance between runs. By the third run Surface Pro 3's performance recovers a bit, although it's still a few percent below the initial, cool run.

PCMark 8 v2 also plots CPU temperature and frequency throughout the course of the benchmark. Unfortunately I don't think I can export the data so I'm forced to present screenshots from the benchmark harness itself. Thankfully even looking at these screenshots is enough to tell us what's going on between the two Surface Pro devices:


Surface Pro 2 PCMark 8 v2 Work Suite


Surface Pro 3 PCMark 8 v2 Work Suite

Both devices do a good job of reaching max turbo fairly regularly, but Surface Pro 2 appears to spend more time at its max turbo state. By the last loop of the benchmark Surface Pro 3's max power is limited (green line) by the time we get to the video chat workload, I suspect that is where we lose a bit of performance. I'm only looking at the last of three suite runs here, if we looked at the second one the results would be even worse.

I haven't tested Surface Pro 3 in Microsoft's new docking station so I don't know if the device changes its thermal profile at all when docked, but in tablet or laptop mode it's definitely going to throttle quicker than Surface Pro 2 did. I must stress that I don't think this is necessarily a bad idea. Surface Pro 3 improves usability over Surface Pro 2 by leaps and bounds, and it's still faster under load than the original Surface Pro. All of this comes at the expense of reduced sustained performance. As you'll see from the rest of our tests, peak performance did get better over last year's model.

Fan Noise

Surface Pro 3's single fan is more noticeable than in Surface Pro 2. The sound it produces isn't necessarily louder, and when spinning it sounds a lot like any other Ultrabook with a fan in it. Compared to Surface Pro 2, the fan does kick in more frequently. For light tablet workloads or even light office work on Surface Pro 3, the fan remains silent. It's only when you're doing anything CPU or GPU intensive that you'll hear it spin up. The big difference is that in situations where you wouldn't hear fans spinning on Surface Pro 2, you'll sometimes hear it on SP3. This is the tradeoff that comes with the thinner chassis.

The New Type Cover & Pen Battery Life
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  • PaulC543 - Thursday, June 26, 2014 - link

    "But your claims are just ridiculous... An iPad Air weighs only 1 pound..the iPad mini weighs much less. Adding a tablet to a notebook doesn't add "Several times the weight/bulk" it's not even 1-time the weight and bulk"

    You misunderstood what I said. What I meant was that carrying a separate tablet and a separate laptop ends up costing more and the combined weight is several times what the Surface is.

    An iPad Mini (~$400 and .73lbs) plus a comparable laptop (roughly $1000 and 3.5 lbs) would equal the cost of a Surface Pro and type cover and weigh about 4.25 lbs to the Surface's 1.75lbs. That's several times in anyone's book. Swap the iPad Mini for an Air, and you're spending $400 more still and gaining another 1/4 lb. Throw in the weight of 2 changers, wires, cases, etc.

    And sure, there are advantages to having two separate devices, but there's also disadvantages (weight/bulk/integration/file transfers, etc.), so it's 6 to 1, 1/2 dozen the other. But that comes down to personal preference and isn't really what I take issue with - I take issue with the baseless complaints (not necessarily directed at you) that the Surface fails at everything. It doesn't, it's actually quite good at most things, and excels at others. In fact, the Surface has fewer absolute negatives than either laptops or tablets - laptops are too bulky in both design and weight for tablet tasks, and tablets are essential absolutely incapable of laptop-class capabilities. The Surface may require some modest compromises at the extremes of those two use scenarios, but it's still plenty capable at them and covers the entire range in between.
  • mkozakewich - Monday, June 30, 2014 - link

    This isn't targeted towards the masses, really. Like this, I'd also find myself hard-pressed to recommend the Macbook Air to someone who just need a mass-appeal notebook. They can get what they want and save $400 by getting some kind of generic pseudo-ultrabook.

    Same for the iPad. There are specific cases where I might recommend it, but for most people I'd explore things like the Nexus 7 first.
  • anandbiatch - Monday, June 30, 2014 - link

    Alienware

    lolwut?
  • ymcpa - Monday, June 23, 2014 - link

    Are you saying that laptops and tablets aren't compromises? The laptop doesn't have the power of a desktop but add portability. The tablet doesn't have the power, screen size, or keyboard of a laptop but adds more portability and works well with content consumption and light gaming. The question is how much are you giving up in the compromise and what your needs are. As a laptop the surface gives up some comfort on your lap and the keyboard isn't as good because of the shallow keys. You get a lighter device that pretty much has the same processing power as most laptop(obviously excluding gaming laptops with dedicated graphics). As a tablet you are sacrificing weight and battery life but are getting a more power device that can convert to productivity when needed and access to desktop apps. There is an app gap for mobile apps, but that has been steadily improving and you do have access to a desktop browser that will give you access to the content of many apps which aren't yet available on win 8. The other tablets can't access these sites and need the apps to access content.
  • PaulC543 - Tuesday, June 24, 2014 - link

    I love the insinuation that tablets and laptops themselves carry no compromises. The suggestion is patently absurd:

    Tablets - low performance, limited memory and storage, imprecise input, poor integration into a network, severely limited app capabilities, OS update support of maybe 3 years max.

    Laptops - large footprint, inefficient input (trackpads), and unless you spend a lot of money thick/bulky, heavy, no touch screen.

    *ALL* systems are compromised in one way or another, the Surface line just throws a net around a different set of attributed, and it's neither right or wrong for doing so. If the features it covers aren't important to you, then it's not the right device for you.

    Personally, tablets (iPad/Android) are utterly useless to me, while I don't have sufficient need for optimum typing performance to justify the bulk of a clam shell design. So for my needs, the compromises the Surface makes in laptop and tablet modes are minimal, and a small price to pay for the huge area it covers between those two form factors.

    In the Surface Pro, I've found very few compromises, and the ones that it does make aren't ones I find particularly limiting.
  • mkozakewich - Monday, June 30, 2014 - link

    All laptops but one aren't the best laptop. All tablets but one aren't the best tablet. By definition.

    Usability weirdness aside (which is entirely different for every person, positive or negative), the PC internals of the Surface Pro are very competitive. You don't get the absolute max battery life, if that's the one thing that defines value to you, but there are levels for pretty much everything else to make it what you need at a cost similar to other laptops of that power.

    Meanwhile, it also makes a pretty good tablet. It's not really supposed to be competing with the iPad; it's really for the people like me who like the idea of a tablet but don't need one and don't want to spend the extra $500 on an iPad.
  • skiboysteve - Monday, June 23, 2014 - link

    Great review! If I had the budget I would buy one. Seems like MS iterated quickly so they could nail it. Wonder what they will try next.

    For the prolonged performance thermal concerns... I wonder if the office / productivity benchmarks actually mimic the timing of what a user would actually do? Do they just benchmark a ton of office tasks back-to-back-to-back that a user wouldn't normally do that fast? In that case I doubt a user would run into it. Games on the other hand... would be a problem. I wonder if a similar technology like nVIDIA's frame rate limiter would be great here.
  • mkozakewich - Monday, June 30, 2014 - link

    For a long time now, Intel's boosting meant that their cores would work a lot better with proper cooling. The same holds true today: If you docked the Surface Pro 3 with a dock that thermally mates with the backside (Ooooh my) and uses additional, bigger fans to provide better cooling, you'd get far better performance. I think AnandTech actually had articles a couple years ago where they talked about those possibilities.

    At the moment, I don't think Microsoft's dock has any fans, so it just adds dead weight to the back of the device, which I assume would just cause even worse thermals. Let's hope they add in additional active cooling (or at least good passive cooling, with some kind of fin structure) to their docks in the future. Then they'd at least be worth that price.
  • djw39 - Monday, June 23, 2014 - link

    Anand: still seeing distorted aspect ratio on the pictures in this site's articles, only when viewing in portrait mode on Android (chrome) (Optimus G). When I rotate to landscape the pictures look right.
  • drmyfore - Monday, June 23, 2014 - link

    WEIGHT:
    Surface Pro 3 / 800g (+295g TypeCover=1095g)
    Macbook Air 11 / 1.08kg
    Macbook Air 13 / 1.35kg

    RES:
    Surface Pro 3 / 2160*1440
    Macbook Air 11 / 1366*768
    Macbook Air 13 / 1440*900

    THICKNESS:
    Surface Pro 3 / 9.1mm (4.8mm TypeCover=13.9mm)
    Macbook Air 11 / 17mm
    Macbook Air 13 / 17mm

    BATTERY LIFE (OFFICAL):
    Surface Pro 3 / 9H
    Macbook Air 11 / 9H
    Macbook Air 13 / 12H

    Why not compare with Air 11?

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