I have experienced a MASSIVE amount of "chattering" noise inside the FF800 when ON. It's very intermittent, but when it starts, can continue for quite some time. Power cycles do not seem to solve it, nor does AutoSync vs. Master on Clock Mode or whether any peripherals attached to it are powered up or down. It's connected via Firewire 800 to MacPro (1st generation) running Mac OS10.5.8  and 2.62a Fireface settings with latest firmware updates v2.70 and Kernel drivers v2.55

Any ideas or suggestions greatly welcomed!