Centrino go
The final and most familiar of the trio is Intel's latest Montevina mobile platform, known as Centrino 2. Montevina has been around since the summer and introduces Intel's G45 integrated chipset to the mobile arena. Platform enhancements over the previous Santa Rosa Centrino platform include a faster 1,066MHz bus and support for the DDR3 memory. The latter brings lower operating voltages and hence improved power consumption. But it's the G45's integrated graphics that really mark a break from the past.
It's Intel's first platform to have a truly modern 2D video decode engine and, on paper at least, it matches AMD and Nvidia with hardware decode support for VC-1 and AVC, as well as HDMI output and HDCP encryption. It's a fully featured mobile HD solution. Intriguingly, it also supports hybrid graphics. Intel doesn't have its own discrete graphics chip yet (that will have to wait until a mobile version of the Larrabee chip arrives, probably no sooner than 2011). This feature allows Intel to pair its IGPs with another vendor's discrete chip, therefore maintaining full 'ownership' of the platform.
Pixel performance
If that's an overview of how the three platforms compare for features, we now come to the really tricky bit: performance. Laptop designs vary hugely, so drawing conclusions – particularly regarding metrics like battery life – is fraught with dangers. Nevertheless, there are a number of key points.
Firstly, Intel has done a pretty decent job with its first effort at hardware decode support for HD video. The Centrino 2 representative in our group of notebooks – a Sony Z Series laptop – and the GeForce 9400M Apple MacBook are powered by the same Intel Core 2 processor.
To allow a direct like-for-like performance comparison, the MacBook was running Microsoft Vista Ultimate 32-bit during our test. While Centrino 2's decode of our AVC Blu-ray video stream was not quite as effective as the 9400M's, it still kept CPU usage well below 10 per cent when running on mains power.
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The fact that the Puma-powered Asus M51T clocked up 15 per cent CPU usage in the same test probably reflects inferior CPU power more than it does the ability of the Radeon HD 3200's AVIVO decode engine.
Battery life
On battery power, the comparison is clouded by varying power-saving implementations. The MacBook's basic Vista installation is much less aggressive in this regard than the Sony's, which explains the large gap in CPU usage during Blu-ray decode – 7.9 per cent versus 25.8 per cent. As for the Asus laptop, while its average of 45.1 per cent seems acceptable on battery power, it came dangerously close to dropping frames with a peak CPU usage of 81.3 per cent.
As for battery life during HD decoding, after playing back a full Blu-ray movie from the hard disk (hard disk playback was necessitated because only the Asus had an integrated Blu-ray drive), the Sony retained an impressive 62 per cent of its battery capacity, with the MacBook next on 49 per cent. Unsurprisingly, given its large 15.4in screen, the Asus brings up the rear with just 45 per cent of its battery capacity remaining.
How much this reflects on the power profiles of the mobile chipsets themselves is hard to judge. With differing screen sizes and battery capacities, there are simply too many variables. The good news is that all three systems allow you to watch an HD movie and have power left over. The final piece of the HD video playback puzzle involves decoding video streams without hardware support. Exactly how important this is will depend upon your video watching habits.
HD video
By far the most popular codec for user-encoded HD content is currently X264. It's very closely related to AVC / H.264, but currently, hardware acceleration support from AMD, Intel and Nvidia's decode engines is patchy at best. You simply cannot rely upon it. Admittedly, much of the X264-encoded content in circulation on various file-sharing networks is illegal. But X264 is also legitimately used to compress free-to-air HD digital TV capture streams into more manageable file sizes for private use.
Our testing of a full 1080p X264 stream is very revealing. On battery power, Asus's Turion CPU simply can't cope, delivering an extremely stuttery performance. Both of the Intel-powered systems have no problem achieving smooth playback, either on mains or battery power. The bad news for AMD, then, is that it must come last in this three-way contest. There is nothing wrong with the Puma platform itself, but it's let down by the substandard Turion CPU.
A worthy second place spot goes to Centrino 2. Intel deserves credit for making quality HD support a mainstream feature.
But our winner has to be Nvidia's impressive GeForce 9400M. Its single-chip architecture is the best approach for mobile PCs, and it has marginally the best HD decode acceleration and comfortably the fastest 3D performance.
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First published in PC Plus issue 278
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