Technology AnandTech: AMD vs. Intel: Battery Life Investigated

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AnandTech: AMD vs. Intel: Battery Life Investigated
By Jarred Walton - August 5th, 2009

Anyone looking to go out and purchase a new laptop is almost certainly interested in a couple things: how much does it cost, and what sort of battery life can you expect? Answering those questions for any specific laptop is simple enough, provided we can get a sample unit for testing. However, it becomes more difficult to answer these questions when you're looking at the big picture -- i.e. AMD vs. Intel laptops. The pricing question is easier: laptops using AMD platforms are (usually) cheaper than equivalent Intel platform laptops. That's simple enough: you're paying more for the Intel brand. But what about battery life?

We have long tried to answer that question, but the best we could do up until this point was to compare "similar" laptops. Getting the same LCD, hard drive, optical drive, and most importantly battery has been very difficult -- so difficult that we have not been able to do it. A few manufacturers offer competing AMD and Intel laptops with very similar specifications, but no one seemed willing to send their AMD-based system. Were they afraid of cannibalizing sales of their more expensive laptops? Did they just think that an AMD-based laptop wouldn't stand up well in our testing? We don't know for sure, but what we do know is that Gateway has stepped up to the plate and sent us two all but identical laptops. We've been busy the past week or two putting the laptops through our test regimen, and we will have the full review shortly. In the meantime, we thought you might be particularly interested in the battery life you can expect.

The chassis are identical from the outside, and everything else is the same as well other than the motherboard, chipset, and processor. Both come with 4GB DDR2 memory, a 15.6" 1366x768 LED backlit LCD, 320GB 5400 RPM hard drive, and a DVDRW. Both also include Gigabit Ethernet and 802.11n WiFi (Intel WiFi Link 5100 for the NV58 and Atheros AR928X for the NV52). In fact, even the CPUs have the same 2.1 GHz clock speed -- not that CPU clock speed matters -- as well as 35W TDP ratings -- not that that matters either, as we'll soon see. On the AMD side, we have the QL-64 (65nm, 2.1GHz, 2x512K L2, 3600MHz HyperTransport bus), and on the Intel laptop we have the T6500 (45nm, 2.1GHz, 2MB shared L2, 800MHz FSB). We should also mention that the NV58 costs more than the NV52, $500 for the NV52 and $580 for the NV58. What does the extra $80 buy you?

We will have performance numbers in our upcoming full review, but considering this is a match between AMD's old dual-core Athlon 64 X2 (K8 architecture) and Intel's Core 2 Duo, you can probably already guess the results. Intel is quite a bit faster in all of the CPU benchmarks. On the other hand, the AMD platform comes with much better integrated graphics, so if you would like to do a bit of 3D gaming on occasion (at low to medium detail levels) AMD easily wins the graphics benchmarks. Now let's look at battery life.

Both laptops used identical power saving settings under Windows Vista's "Balanced" plan (with some minor tweaks to the defaults on both systems). We ran five different test scenarios, ranging from best-case idle battery life at the Windows desktop to a far more taxing DVD/x264 playback results, along with two different Internet surfing benchmarks. One Internet benchmark represents a "light" load while the other has far more Flash content and represents a "heavy" load. We set both LCDs to 100 nits brightness (40% in this case) and completed a couple charge/discharge cycles to break in the battery before beginning our tests. Here are the results.






Considering these systems are as close as we can get to "identical", AMD takes a real pounding in battery life testing. The closest result (the idle test) has the Intel platform providing 20% more battery life, while the best Intel results (DVD playback and heavy web surfing) give about 35% more battery life. Averaging all five results, the Intel-based NV58 delivered 28% more battery life than the AMD-based NV52. Ouch.

Obviously, despite having identical clock speeds there are some real differences between the two processors. For one, Intel's T6500 is a 45nm part compared to the 65nm QL-64 (not that AMD has 45nm parts yet). We also don't know how much of an impact the various chipset and motherboard components might have. What we do know is that AMD's current mobile processor lineup consists of dual-core CPUs that range from 2.00GHz up to 2.50GHz, with most having a 31W TDP to 35W TDP rating; the TK-42 is a 20W 1.60GHz part and the QL-62 is a 25W 2.00GHz part. Intel on the other hand has many more options. 10W dual-core CPUs are available with clock speeds of 1.06GHz to 1.60GHz; 17W chips have clock speeds ranging from 1.33GHz to 2.13GHz; 25W processors start at 2.26GHz and end at 2.66GHz; and the 34/35W parts cover the gamut from 1.60GHz all the way up to 3.06GHz… and that's just the Core 2 Duo parts! Pentium Dual-Core, Core 2 Quad, and Core 2 Extreme parts are also available to flesh out the spectrum. Then again, some of those parts cost twice as much as the Gateway NV52 just for the CPU.

When Intel released Banias and the Centrino platform in March 2003, they started a revolution in their approach to mobile processor design. Power and efficiency became the focus rather than pure clock speed, and the result has been much better mobile processors when it comes to performance per Watt. Unfortunately for AMD, they appear stuck with the old way of doing things: build a generic architecture and then optimize it for power requirements on mobile chips. Essentially the same core K8 architecture that launched in 2003 continues to power AMD's mobile offerings, and while the ensuing shrink to 65nm has helped there's still a lot of ground to make up. AMD-based laptops are still more than fast enough for most users -- and let's make this clear, a $500 dual-core AMD laptop is tons faster than anything using Intel Atom (though it uses more power, obviously) -- but Intel has the upper hand. It's unfortunate there's not more competition in the mobile processor space, or we might start really start to see prices drop!

For now, if you're looking for an inexpensive laptop (not a netbook), you need reasonable battery life, and you don't care about graphics performance we suggest saving up the extra $50-$100 for an Intel-based system.

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Bottom line: Intel spanks AMD. If battery life in one of your primary concerns, get an Intel processor.
Bottom line: Intel spanks AMD. If battery life in one of your primary concerns, get an Intel processor.

Not to mention, AMD's slipping in the mobile game - Intel is faster and more power-friendly. And the next generation of Core 2 mobile chips will be even smaller and faster yet (another process shrink).