Corsair's three pre-installed fans are clearly getting a good supply of clean air. Our Core i5-3570K processor, running at 4.4GHz, is kept suitably cool during a demanding Prime95 stress test.
GPU cooling performance is good, too. The 450D isn't quite as promising as chassis with mesh side panels or dedicated GPU fans, yet under-load temperature when gaming is well within the limits.
As you might expect from a performance chassis, noise levels are slightly higher than average. 550D aside, the Obsidian Series has never made silent-running a priority, and the 450D is no exception.