Let’s look at performance from two angles, first cooling. The Smart Fan 2 does a very good job at cooling. While it was running at full speed it lowered the temperatures on my CPU by 5C in idle, and 3C at full load. The drawback, it is loud. Next I tested it using the thermal probe, which is how I see most people using it, especially if they put it on a CPU like I did. I slid the probe between the heatsink and CPU with a little Arctic Silver and fired up the system. The fan did not run at full speed, and was therefore much quieter. Even at the slower speeds idle and load temperatures were 2-3C lower. As the CPU heated up, the fan sped up.