Review Index:

Nvidia GeForce GT 640M Review: Kepler Arrives For Mobile

Subject: Mobile
Manufacturer: Nvidia

Introduction, GT 640M Basics

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About two months ago I wrote an less than enthusiastic editorial about ultrabooks that pointed out several weaknesses in the format. One particular weakness in all of the products we’ve seen to date is graphics performance. Ultrabooks so far have lacked the headroom for a discrete graphics component and have instead been saddled with a low-performance version of the already so-so Intel HD 3000 IGP.

This is a problem. Ultrabooks are expensive, yet they so far are less capable of displaying rich 3D graphics than your typical smartphone or tablet. Casual gamers will notice this and take their gaming time and dollars in that direction. Early leaked information about Ivy Bridge indicates that there has been a substantial increase in graphics capability, but the information available so far is centered on the desktop. The version that will be found in ultrabooks is unlikely to be as quick.

Today we’re looking at a potential solution - the Acer Aspire Timeline Ultra M3 equipped with Nvidia’s new GT 640M GPU. This is the first laptop to launch with a Kepler based GPU. It is also an ultrabook, albeit it one with a 15.6” display. Otherwise, it isn’t much different from other products on the market, as you can see below.

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This is likely to be the only Kepler based laptop on the market for a month or two. The reason for this is Ivy Bridge - most of the manufacturers are waiting for Intel’s processor update before they go to the trouble of designing new products.

Continue reading our review of the NVIDIA Kepler GT 640M GPU in an Ultrabook!!

Normally we’d jump right in to the laptop review, but this is a special case. We’re looking at the first example of a laptop using a new architecture. Here we will take a look at the performance of the Nvidia GeForce GT 640 specifically. We will publish a separate, comprehensive review of the laptop at a later date.

In addition, while we are able to share with you the performance of the GeForce GT 640M, we’re not able to dive too deeply into the architecture because some information is still under NDA. At this time we’re only able to talk about the GeForce GT 640M as it relates to this laptop.

Kepler For Laptops - What We Can Say

Editor's Note: Yes, this is the same Kepler architecture that you will soon find in discrete graphics cards as well and is the first GPU from NVIDIA built on the TSMC 28nm process technology.  We are going to have to wait to give any of the details of the new architecture a little longer but since this notebook is already on sale in Asia, we were given the go ahead to publish this performance overview.  Enjoy!

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Nvidia made it very clear that performance per watt was their primary concern during the design of the Kepler architecture. In a way, this seems obvious - this area is important for any new processor. But the focus on power consumption is telling. Nvidia was burned by its Fermi architecture because AMD’s components were able to provide similar performance with much lower power consumption. The green team didn’t want to see that happen again.

The performance numbers thrown out by Nvidia are aggressive. The company claims that its new GT 640M will be able to provide a playable experience at 1366x768 with high detail settings in all of the most demanding titles released last year. This means titles like Battlefield 3, Skyrim and Batman: Arkham City. All of these should run at 30 FPS or better on a GT 640M.

The part in our Acer Aspire review unit came paired with 1GB of DDR3 memory. The GPU clock is 625 MHz , the Memory clock is 900 MHz and the Shader clock is 1250 MHz. The GPU clock and Shader clock are actually down a fair bit in comparison to the GT 540M, and in addition to that, the amount of memory available is also a bit conservative. 

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You might be wondering how this new part can offer decent performance with relatively low clock speeds and modest memory. Part of the answer is in the architecture. Kepler is all new, and while the older GT 540M contained just 96 CUDA cores, this new part serves up 384.

Unfortunately, this is all that we can share with you about the architecture at the moment. Until the NDA lifts fully we are only able to provide information that an end-user of this laptop could discover. Look for a deep-dive into the architecture when Ryan is able to publish his review of the new Kepler desktop part. 

So, let's get to the benchmarks.

Video News

March 13, 2012 | 09:38 PM - Posted by Anonymous (not verified)

When does the NDA lift?

March 13, 2012 | 10:05 PM - Posted by Brian (not verified)

Way to go trolling the internet: "Kepler preview tonight".

No one gives a shit about mobile. Give us GK104.

March 13, 2012 | 10:10 PM - Posted by Ryan Shrout

Hey, I said mobile Kepler in my post!

March 13, 2012 | 10:11 PM - Posted by Eggrenade

"...they so far are less capable of displaying rich 3D graphics than your typical smartphone or table."


March 13, 2012 | 10:48 PM - Posted by Ryan Shrout

We have some fancy technologically advanced tables here at PCPer.



March 13, 2012 | 10:16 PM - Posted by Rahul (not verified)

Can you give more information about the memory interface? Was it 64-bit, 128-bit etc and what is the net available bandwidth? Is there any "driver info" dialog or something similar and if so, can we get a screenshot? Not familiar with nvidia's interfaces, but AMD Catalyst has a "hardware info" dialog.

March 13, 2012 | 10:35 PM - Posted by Matt Smith

According to GPU-Z the bus width is 128 bit with a total bandwidth of 28.8 GB/s.

March 13, 2012 | 10:17 PM - Posted by Rahul (not verified)

Also thanks for providing this review. Pretty intriguing :)

March 13, 2012 | 11:51 PM - Posted by Anonymous (not verified)

Ryan, are you sure you have the right information for the 555M?

The version of the 555M that has a GPU clock of 753 MHz only has 96 CUDA cores, and the version that has 144 CUDA cores has a GPU clock of 590 MHz. As far as I know, there's not a version that has 144 CUDA cores and a 753 MHz clock.

Also, Alienware's website lists the card as having DDR3 memory, which is found on the 144 CUDA Core 590 MHz version of the 555M. The other version uses GDDR5 so it seems likely that the GPU clock is not 753 MHz.

March 14, 2012 | 09:15 AM - Posted by Ryan Shrout

Just going of the "up to" specs.

March 14, 2012 | 01:04 AM - Posted by zarga (not verified)

So basically it performs around 20% better than the ATI 6750M, thats a nice figure if the power consumption is low.

Anyway, how does that Acer qualify as an Ultrabook?? There are plenty of 15" laptops out there with the similar weight/size characteristics, fast CPU and bigger battery at the same time. For an Ultrabook, the Acer is too heavy, for being a proper workstation laptop its clearly underpowered.

March 14, 2012 | 06:50 AM - Posted by Anonymous (not verified)

Fix this nonsense:
"The GPU clock is 625 MHz , the Memory clock is 900 MHz and the Shader clock is 1250 MHz."

March 14, 2012 | 09:16 AM - Posted by Ryan Shrout

What is the "nonsense" here?

March 14, 2012 | 04:22 PM - Posted by Anonymous (not verified)

shader clock is.
no hotclock for kepler

March 14, 2012 | 07:52 PM - Posted by Ryan Shrout

You think...?


March 14, 2012 | 11:43 AM - Posted by Anonymous (not verified)

Are those temps fahrenheit or celsius?

March 14, 2012 | 10:25 PM - Posted by Matt Smith

Fahrenheit! If it was Celsius I'd stop playing games and start using the laptop as a hotplate.

March 14, 2012 | 02:26 PM - Posted by Anonymous (not verified)

So Kepler does have Shader hot clocks?

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March 14, 2012 | 04:32 PM - Posted by Anonymous (not verified)

can you tell something about the fixed function units?
the GT 540m had something around 4 ROPs and 16 TMUs I think, the 555m 1.5GB 24/32, what about the 640m?

March 20, 2012 | 03:07 PM - Posted by Anonymous (not verified)

I just want the mobile version of keplar to come out so i can have a decent gamming laptop for college >.>

December 14, 2012 | 03:49 PM - Posted by Anonymous (not verified)

Hi, i have this graphic card on another laptop, and it reaches 84 Celcius when playing a game like far cry 3, is this too hot for this graphic card or can it take the heat?

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