Judged by normal metrics of PC processor performance and value, the AMD Athlon II X4 610E looks like a loser. It's much more expensive, for instance, than the Athlon II X2 620 but clocks in slightly slower at 2.4GHz to the 620's 2.6GHz.
Consequently, the cheaper chip is slightly quicker across the board. But for a low power chip, relative performance is less critical. What matters is whether the Athlon II X4 610E delivers enough performance to get the job done in return for significantly less wattage.
On the first count, the 610E gets the thumbs up. With four cores, it has ample processing power for decoding high definition video streams of most kinds. Only badly encoded Flash video streams present a problem.
Slightly less convincing, however, is the efficiency part of the package. Compared to the 620, the 610E does use less power under load. But the difference isn't as dramatic as you would expect from AMD official ratings. Rather than a 50 Watt advantage, our testing indicates the reality is more like 25 Watts.
As for overclocking, you might think it hardly applies to a low power chip. However, there's actually a closer relationship between high efficiency and high clockspeeds than you might think. In both cases, chips that leak less power tend to be more effective. It's slightly disappointing to find, therefore, that the 610E overclocks no better than its full-power sibling, even if 3.6GHz is a decent result in isolation.
If you want to maximise performance in a power and thermal-critical package, the Athlon II X4 610E is worth a look. It's around 25 Watts more efficient than a standard quad-core Athlon II X4. Meanwhile, it delivers plenty of performance for a home cinema system.
Unless improved power efficiency is a must, the 610E's premium pricing is a problem. It's slower than quad-core chips costing half as much. It's also not as power efficient as AMD's specs would have you believe and doesn't deliver spectacular overclocking headroom.
Worth a look for home cinema fans. Too expensive for everyone else.
Follow TechRadar Reviews on Twitter: http://twitter.com/techradarreview