The Asus EAX1650XT cannot be overclocked with ATI Catalyst or the latest version of ATI Tool. We tried to find the max core frequency but in all cases, the system crashed.
The card has an average copper based air cooling system. While the rotating fan is small, it does make a lot of noise, especially under full load. We weren't very happy with the air cooling solution that Asus has chosen for the X1650XT series. Imagine that with two cards, the noise is even worse.