Conclusion: Not Meant For The High End
The fan regulation worked absolutely reliably during our tests and achieved its goal of noticeably reducing the noise produced by the fans.
On the downside, the automatic fan-speed adjustment through the temperature sensors still needs some work.The processor in our testing system, an Athlon64 3400+, ran at a high temperature when tasks with a high CPU-load were run. Sadly, the Ultracool II did not seem to consider this a reason to increase the fan speed by an appreciable degree. In light of the device's price, which comes in at around $40 (€40), we would have like to see ability to manually adjust certain threshold temperatures and, of course, set a minimum rpm for the fans. After all, it's better to be on the safe side.
Nonetheless, the Ultracool II should work without problems in any system safely below the 3 GHz barrier. On the AMD side of things, that means Athlons below 2 GHz (max. 2800+). Of course, a sensible placement of the sensors is of the highest importance, in any case. And if you don't like the aluminum look, the Ultracool II is also available in a version with black varnish.