Making a processor like the Athlon II X2 240e is something that AMD wouldn't have been able to do even a year ago, when the company was stuck on a 65nm manufacturing node and its processors tended to suck a lot of power and make a lot of heat.

AMD's current generation of Phenom II and Athlon II processors have trimmed off a lot of that excess power usage, and AMD has taken advantage of it the smart way. Some of its processors, like the Phenom II, have gotten a much-needed increase in speed to compete with the likes of Intel's Core i5 and Core i7 series of processors. AMD's mainstream processors go in the opposite direction, trading off potential speed increases for very real gains in power efficiency and reductions in price.

The 2.8GHz, $80 CDN ($77 USD, £50 GBP) Athlon II X2 240e takes this design approach even further, and its 45W TDP makes it one of the most efficient processors that PCSTATS has benchmarked. The only processor that used less electricity under load was AMD's Sempron 3600+ chip.

With 2MB of L2 cache and no L3 cache at all, the performance of the Athlon II X2 240e isn't the fastest (in fact it was pretty consistently the slowest), but it remains fast enough for use in office applications and simple tasks like HD media decoding, while running applications like BitTorrent at the same time. It can handle pretty much everything you'd expect from an always-on office desktop computer.

When matched up with AMD's 785G chipset on a microATX motherboard, it's possible to build a tiny Athlon II X2 240e-based system for less than $400. The only real thing stopping the Athlon II X2 240e from sweeping the low-wattage, low-price processor market is that AMD already has another processors just like it in the form of the AMD Athlon II X2 250 processor. The Athlon II X2 250 draws a little bit more power (about 10W) and is a little bit faster (approx. 5-7%) and costs slightly more (around $10).

If you have to choose between the two, you'll likely want the Athlon II X2 250 processor if you're building a primary computer system that will need that bit of extra speed, and the Athlon II X2 240e for a PC that's just staying on in the background. It's a tiny margin though, so either processor can be a winner in the right setting.