Performance
There's huge scope for cooling modifications, but even in its out-the-box configuration, the Obsidian 750D provides ample airflow. The default three-fan setup has absolutely no problem cooling our overclocked Core i5-3570K processor during a stint of Prime95.
Having unobstructed front intakes results in decent GPU temperatures, too, though the 750D isn't quite as impressive as some of the competition in this regard - particularly those that utilise dedicated side intakes.
Having made a brief foray into soundproofing with the Obsidian 550D, Corsair's focus appears to have shifted back to maximum performance. Still, even without soundproofing materials, the 750D manages to keep noise down to a reasonable level.