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NVIDIA GeForce GT 640M: Kepler Goes Mobile
Date: Mar 22, 2012
Author: Dave Altavilla
Introduction and Specifications
Typically mobile graphics launches trail their desktop counterparts by a few months, as major GPU players like NVIDIA and AMD wring out power consumption and performance from their architectures in order to accommodate the tighter thermal and power budgets of notebook form factors. However, NVIDIA has obviously been refining their new Kepler GPU architecture into its various incarnations for while now, because the company is launching a dual salvo of production silicon for both mobile and desktop graphics markets today.  Of course the company has significant motivation for this, with Intel's Ivy Bridge mobile platform just around the corner, backed with DX11 class integrated graphics.

The fact that NVIDIA is ready with both desktop and mobile variants, in and of itself, is fairly impressive but their mobile platform demonstration vehicle may also surprise you.

An Ultrabook with a discrete graphics chip?  The Acer Timeline Ultra M3 sports NVIDIA's latest.

NVIDIA presented us with a 15-inch Acer Ultrabook to show off their midrange mobile chip based on their new GeForce 600M series architecture.  It's just 20mm thin, weighs about 5lbs and claims to offer up to 8 hrs of battery life, though you can bet that figure is not under a gaming workload.

Regardless, NVIDIA obviously decided to step out in current fashion and is looking to up the "ultra" factor in Ultrabooks. Although it seems like an unlikely place for a discrete GPU, NVIDIA's 28nm Kepler design trimmed down to "only" 384 processor cores and a 128-bit memory interface, sips a lot less power than its higher-end desktop counterpart.  Of course, the Acer Timeline Ultra M3 is also a bit larger than most of the 13 and 12-inch Ultrabooks we've looked at thus far as well.  But it's still a pretty svelte and light machine.

Let's look at the specifics of the NVIDIA's new GeForce GT 640M mobile graphics engine...

NVIDIA GeForce GT 640M
Specifications & Features

With a graphics core clock of 625MHz and a 384 CUDA core architecture, you might think the GeForce GT 640M is a higher-end chip, but NVIDIA has a few other higher-end members of the family flanking this one.  At this point, the GeForce GT 640M is the closest successor to the company's previous generation GeForce GT 555M. 

Here's a quick look at NVIDIA's new notebook graphics product stack:
GeForce 610M

GeForce GT 620M
GeForce GT 630M
GeForce GT 635M
GeForce GT 640M LE
GeForce GT 640M
GeForce GT 650M
GeForce GTX 660M
GeForce GTX 670M
GeForce GTX 675M

As you can see, there's a GeForce 600M series now in all segments, but not all are based on the new Kepler architecture.  Here's what a few of the GeForce GT 600M series GPUs look like, beyond the GeForce GT 640M we'll be stepping through today...

NVIDIA GeForce GT Performance GPU Specs

GeForce GT 650M GeForce GT 640M

GeForce GT 640M LE

GeForce GT 635M
Process 28nm 28nm 28nm 40nm 40nm
Architecture Kepler Kepler Kepler Fermi Fermi
Processor Cores Up to 384 Up to 384 Up to 384 Up to 96 Up to 144
Processor Clock Up to 850MHz Up to 625MHz Up to 500MHz Up to 762MHz Up to 675MHz


Up to 2GB


Up to 2GB


Up to 2GB


Up to 2GB


Up to 2GB GDDR5
Memory Width Up to 128-bit Up to 128-bit Up to 128-bit Up to 128-bit Up to 192-bit
Memory Bandwidth Up to 64.0 Up to 64.0 Up to 28.8 Up to 50.2 Up to 43.2

NVIDIA is blending some Fermi designs into the lineup, but re-branding them so as to limit confusion in product placement and performance.  However, there is a fair bit of Kepler technology through the top end of the stack.  NVIDIA's formal press release can be found here. Also, if you'd like a deep dive look into NVIDIA's new Kepler GPU architecture, we'd suggest heading over to our Geforce GTX 680 article for the full low-down.  Marco goes through all the heavy lifting and details there.
Up Close with the Acer Timeline Ultra M3
The Acer Timeline Ultra M3 is what we'd call a bit of a "tweener."  At $799 MSRP, this machine is definitely one of the less expensive Ultrabook options on the market right now, especially if you consider it's sporting one of NVIDIA's latest GPUs under the hood.  The machine you're looking at here may not come to the US exactly as you see it and may differ in certain areas.

Unfortunately for us, the Ultrabook experience here falls a bit flat in spots, since build quality doesn't measure up to what we've seen from the likes of Asus, Dell and Lenovo.  This machine's chassis is an all plastic affair and the keyboard feels a tad spongy in spots.  The machine is very thin (only 20mm), especially for 15-inch model but unfortunately all of the major ports are on the rear of the notebook, except for its SD card slot; which by the way is a nice addition that isn't often enough found in Ultrabooks these days.  The Timeline Ultra M3's display is reasonably bright and sharp but again, with 15" of real estate, we were hoping for a bit more than its native resolution of 1366X768.

No guts, no glory, so we opened it up... A single PCB

Our test machine came configured with an Intel Core i5-2467M dual-core CPU that has a base frequency of 1.6GHz and Turbos up to 2.1GHz, along with 4GB of DDR3-1333 RAM, a 500GB HDD with integrated Solid State Drive, and of course NVIDIA's GeForce GT 640M GPU.  The Timeline Ultra M3 does support NVIDIA's Optimus dynamic switching technology, to conserve power consumption and shutdown the GPU on the fly when it's not needed.  As you can see above, the good majority of all this technology is crammed on to a single PCB, save for things like system memory and WiFi radios.  In the flesh, it really was an impressive internal design to behold. 

And as you'll see in the pages ahead, for NVIDIA and Acer to figure out how squeeze this kind of performance and horsepower into such a wafer-thin form factor is a technological marvel for the most part as well.

Test Methodology, PCMark 7 and 3DMark 11
Test Methodology: As you'll note in the following pages of benchmarks, we've compared the Acer Timeline Ultra M3 with NVIDIA's new GeForce GT 640M GPU versus a few different machines, both standard notebooks and ultrabook class products. In every test case, we tried to leave each notebok as delivered to us from the manufacturers. This meant, after any pending Windows updates were installed, we disabled Windows update and also disabled any virus scanning software that may have been installed, so it wouldn't kick in during benchmark runs. That said, it's virtually impossible to ensure identical system configurations between notebooks; so we'll caution you that reference scores from the various test systems are listed in order to give you a general feel for performance between these similar class of machines and not for direct, apples-to-apples comparisons.

NVIDIA's Optimus control panel with game profiles at the ready...

PCMark 7
General System Performance
Futuremark's PCMark 7 is the latest version of the PCMark suite, more recently released. It has updated application performance measurements targeted for a Windows 7 environment. It combines 25 individual workloads covering storage, computation, image and video manipulation, web browsing, and gaming.

This benchmark is more to set a baseline for you on general system performance.  Here, the Timline Ultra M3's slower CPU and hard drive aren't doing it any favors versus the other Ultrabooks in our test field.  This benchmark only utilizes the GPU in a few tests and in those tests, workloads are very light.  So, in short, this benchmark might be indicative of what Acer's machine can do in general desktop performance but it doesn't showcase what NVIDIA is looking to wave the flag for today.

Futuremark 3DMark 11
Synthetic DirectX Game Benchmarks

Futuremark 3DMark11

The latest version of Futuremark's synthetic 3D gaming benchmark, 3DMark11, is specifically bound to Windows Vista and WIndows 7-based systems due to its DirectX 11 requirement, which isn't available on previous versions of Windows. 3DMark11 isn't simply a port of 3DMark Vantage to DirectX 11, though. With this latest version of the benchmark, Futuremark has incorporated four new graphics tests, a physics tests, and a new combined test. We tested the graphics cards here with 3DMark11's Extreme preset option, which uses a resolution of 1920x1080 with 4x anti-aliasing and 16x anisotropic filtering.

With our first 3D gaming test, we've changed the competitive field to standard notebooks with discrete GPUs.  For gaming, our database of results with the current crop of Ultrabooks is limited. But then again, with virtually all of them thus far driven only by Intel integrated graphics, it doesn't make much sense to compare to them, since you already know what the result will be versus NVIDIA's latest.  In 3DMark 11, versus NVIDIA's previous gen GeForce GT 555M GPU in the Alienware M14x, the new Kepler-based GeForce GT 640M offers up a sizable performance gain; and that's even with a much more powerful CPU backing up the mid-sized Alienware gaming notebook. Early signs here are that mobile Kepler is no joke.

Far Cry 2 DX10 Gaming

Far Cry 2 Game Test
DX10 Timedemo Benchmarking

FarCry 2

Like the original, FarCry 2 is one of the more visually impressive games to be released on the PC to date. Courtesy of the Dunia game engine developed by Ubisoft, FarCry 2's game-play is enhanced by advanced environment physics, destructible terrain, high resolution textures, complex shaders, realistic dynamic lighting, and motion-captured animations. We benchmarked the test systems in this article with the FarCry 2 benchmark tool using one of the built-in demo runs recorded in the "Ranch" map.

In this test we've pulled scores from a few lower-end machines, along with the Alienware M14x we showed you previously.  As you can see, the GeForce GT 640M-equipped Acer Timeline Ultra M3 keeps playable framerates up through its panel's native resolution of 133X768.  At this performance level, you can easily add in a bit of anti-aliasing and still get decent frame rates.  Note that the GeForce GT 555M and Intel quad-core in the M14x here is significantly faster than the Acer Ultrabook.  It's likely that, since this game engine is a bit on the older side, NVIDIA still has some driver optimization to go through and the benchmark itself might be a bit more CPU sensitive as well. 

Let's turn up the workload a bit and add in some leading-edge rendering technologies as well, next.

Metro 2033 Performance

 Metro 2033
 DirecX11 Gaming Performance

Metro 2033

Metro 2033 is your basic post-apocalyptic first person shooter game with a few rather unconventional twists. Unlike most FPS titles, there is no health meter to measure your level of ailment, but rather you’re left to deal with life, or lack there-of more akin to the real world with blood spatter on your visor and your heart rate and respiration level as indicators. The game is loosely based on a novel by Russian Author Dmitry Glukhovsky. Metro 2003 boasts some of the best 3D visuals on the PC platform currently including a DX11 rendering mode that makes use of advanced depth of field effects and character model tessellation for increased realism. This title also supports NVIDIA PhysX technology for impressive in-game physics effects. We tested the game resolutions of 1280X720 and 1024X768 with adaptive anti-aliasing and in-game image quality options set to their High Quality mode, with DOF effects disabled.

Historically, we have setup our Metro 2033 testing to lighter workloads and a DX10 rendering mode, for all but high-end desktop replacement notebooks.  Even the venerable Alienware M14x broke into a hard sweat when set to DX11 rendering.  Metro is a proverbial ball buster.  However, even when set to DX11 rendering effects, the GeForce GT 640M-infused Acer Timeline Ultra M3 still manages to outpace the previous generation GeForce GT 555M in the Alienware machine.  Drop the rendering mode back to DX10 settings and that gap widens even further.

Lost Planet 2 and AvP
In these next two game tests, we had more limited reference data to pull from.  Frankly testing mobile platforms in these game engines really isn't something that makes sense unless you're evaluating big, boat anchor-sized desktop replacement machines.  Of course we're not testing that type machine here by any stretch, but we thought it made sense to show you just how far the GeForce GT 640M can hang.

 Lost Planet 2
 DirectX 11 Gaming Performance

Lost Planet 2

A follow-up to Capcom’s Lost Planet : Extreme Condition, Lost Planet 2 is a third person shooter that takes place again on E.D.N. III ten years after the story line of the first title. We ran the game’s DX11 mode which makes heavy use of DX11 Tessellation and Displacement mapping and soft shadows. There are also areas of the game that make use of DX11 DirectCompute for things like wave simulation in areas with water. This is one game engine that looks significantly different in DX11 mode when you compare certain environmental elements and character rendering in its DX9 mode versus DX11. We used the Test B option built into the benchmark tool and with all graphics options set to their High Quality values.

This grouping zooms in on where the new GeForce GT 640M mobile graphics processor sits in terms of overall performance versus previous gen NVIDIA mobile GPUs.  Here the GeForce GT 640M is roughly 25% faster than the GT 555M and about 5% behind the GeForce GTX 460M.  We'd also offer that this game title accentuates the differences in the previous generation architectures and Kepler, since it makes heavy use of leading-edge DX11 effects like Tesselation and Displacement mapping, as well as DX11 DirectCompute.

 Alien vs. Predator
 DirectX 11 Gaming Performance

Alien vs. Predator

The Alien vs. Predator benchmark makes use of the advanced Tessellation, screen space ambient occlusion and high-quality shadow features, available with DirectX 11. In addition to enabling all of the aforementioned DirectX 11 related features offered by this benchmark, we also switched on 4X anti-aliasing along with 16X anisotropic filtering to more heavily tax the graphics cards being tested.

In Aliens vs. Predator, we don't have much in terms of notebook reference data for you and can't compare it to Intel's HD Graphics 3000 IGP in the Timeline Ultra M3, because the benchmark won't run unless you have a DX11 compatible graphics engine powering it.  We did enable and disable DX11 rendering effects however, to show you a wider spread of performance numbers.  As you can see, even at the native resolution of the Acer Ultrabook's LCD, frame rates remain playable.

Batman: Arkham City vs IGP

 Batman: Arkham City
 DirectX Gaming Performance

Batman: Arkham City

Batman: Arkham City is a sequel to 2009’s Game of the Year winning Batman: Arkham Asylum. This recently released sequel lives up to and even surpasses the original in some areas, taking place 18 months after the original game's timeline. The game has DirectX 9 and DX11 rendering paths, with support for tessellation, multi-view soft shadows, and ambient occlusion. We tested in DX11 mode with all in-game graphical options set to high quality, at various resolutions.

With the latest Batman sequel, we're able to show you the performance delta between the integrated graphics core in Intel's current Sandy Bridge architecture and NVIDIA's GeForce GT 640M.  Note that the Intel IGP can only run in DX9 mode due to the limitation of its architecture, which, by the way, will change when Ivy Bridge hits in the coming months.  As we noted previously, Intel's Ivy Bridge mobile architecture will bring full DX11 support.  Today, this is what the spread looks like however, with the GeForce GT 640M handily outpacing the Intel IGP, even when comparing DX11 performance on the new NVIDIA Kepler mobile core, versus DX9 on the IGP. Comparing DX11 versus DX9 performance between the two graphics solutions, NVIDIA's architecture is some 60% faster.  Comparing both in DX9 mode, NVIDIA new chip is over 2.5X more powerful.

Battery Life Testing
If you're shopping for an ultrabook you're likely very interested in what kind of battery life you can squeeze out of these featherweight systems. This is perhaps the most important metric, at least for some, and what we have below are examples of worst case and best case scenarios under light and heavy workloads.

Battery Eater Pro Stress Test and Web Browsing Light Duty Test {Title}
Light and Heavy Duty Workloads
The results below are from our combined Battery Eater Pro (worst case) and Web Browsing only (almost best case) tests. BEP beats on the CPU, GPU, disk and memory while it renders a 3D image and rotates it in real time on the screen. Our light duty, web browser test refreshes a web page of mixed text, graphics, HTML and Flash, every 3 minutes. Both tests are run with display brightness set to 50% with no sleep timers enabled. All other power plan options are left as delivered from the manufacturer.

We also decided to show what the machine was capable of under a heavy gaming workload, so we looped Far Cry 2 at its highest settings and offer those results here for reference as well.

** Battery Eater test conducted on notebook IGP for Acer Timeline Ultra M3

As you can see, we've got a little more homework to do and we will update this graph to show our best case test condition with the Acer Timeline Ultra M3 under a web browsing only workload.  For now, in the existing data we have, though this Ultrabook has the latest in discrete graphics from NVIDIA on board, when running on integrated graphics, in our worst-case battery eater test, the Timeline Ultra M3 competes with the likes of Asus' highly praised Zenbook.  The Timeline Ultra M3 has NVIDIA Optimus technology on board, so it switches to integrated graphics on the fly when the GPU isn't needed for gaming or video workloads.  In that test case, we saw about 2.5 hours of battery life, which will likely extended significantly under the light duty workload of only web browsing.  In terms of gaming battery life, we observed a little over an hour and a half of untethered up-time.

Again, keep an eye on this page as we'll be updating the graph to show Acer Timeline Ultra M3's browsing only figures later today.

Update:  3/22/2012 - 5:40PM EST - The final browsing only result for the Acer Timeline Ultra M3 has been added to the chart above.  Like the larger Alienware machine, the 15-inch Ultra M3's larger battery helps significantly under light workloads and running on the IGP only, with NVIDIA Optimus technology powering down the discrete GPU.

Performance Summary and Conclusion
Performance Summary:  The new NVIDIA GeForce GT 640M offered best-of-class performance in almost every game test condition we threw at it, especially with current DX11 game titles like Batman, Metro 2033 and Lost Planet 2. In general, this new NVIDIA Kepler mobile GPU is about 20% faster than their previous generation midrange performance mobile device, the GeForce GT 555M. In addition, power efficiency versus the previous gen architecture was significantly better.

Two amigos ready for action...

NVIDIA's new Kepler GPU architecture is a resounding success both in terms of their desktop offering and, as we've come to find out here, their mobile graphics solutions as well.  It wasn't long ago that AMD took the wraps off their 28nm Tahiti offering, but it looks as if NVIDIA is lined up to trump that firmly with their 28nm Kepler architecture.  Furthermore, though we don't yet have AMD Tahiti-based mobile solutions to compare to as of yet, if you consider Kepler's significant advantages in power consumption on the desktop, we can almost be assured that the competitive mobile landscape will lay out similarly between the two from a performance-per-watt standpoint.  In short, there's no two ways about it, everything is coming up roses here for team green this spring.

We only wish there were more notebook product offerings to choose from at this point, with Kepler under the hood.  NVIDIA is claiming several design wins with Asus, Lenovo, Samsung, Toshiba and Vizio at this point in time, for various GPUs throughout their GeForce 600M lineup.  If the company is able to get them to market soon, beating Intel's next generation Ivy Bridge integrated offering by a wide enough window, it could bode well for the company on a number of fronts, including the bottom line.  NVIDIA's notes: "GeForce GPUs put the ’ultra’ in Ultrabooks.  We expect numerous Ivy Bridge-based Ultrabooks with GeForce GPUs to be available in the first half of 2012. The GeForce GT 640M can be found in the Acer Aspire M3-581TG Sandy Bridge-based Ultrabook now." 

And of course Intel's Ivy Bridge sports an integrated graphics solution, so comparing the two is a bit of an apples and oranges view anyway.  We would not expect Intel to be able to pull off discrete graphics-level performance but that, we suppose, remains to be seen.

Regardless of the timing, NVIDIA's mobile Kepler solution is here and now, with Acer's machine already shipping.  We would expect more design wins to fall NVIDIA's way in the not so distant future.  For gaming notebooks, high-end utltrabooks and mainstream multimedia laptops, Kepler is a no-brainer and a hands-down Editor's Choice.

NVIDIA GeForce GT 640M Mobile Graphics

  • Great performance-per-watt
  • NVIDIA Optimus switching enabled
  • Leading-edge DX11 support
  • Fits in the thermal/power envelope of an ultralight notebook
  • Total solution cost still very competitive at $799 MSRP for the Acer Timeline Ultra M3
  • Quiet even under heavy gaming workloads
  • Driver optimization still a work in progress
  • Current design-wins announced but not shipping just yet
  • Ivy Bridge around the corner

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