There are so many new features to DSM 3.0 that you really owe it to yourself to explore every icon. The sleek interface uses so much AJAX to the point that it runs virtually like a PC desktop, all within a web browser. One of the things I came across while exploring the Resource Monitor was that my NAS's CPU usage was constantly at 100%. The 1GHz processor has a lot to do since it runs so many services and even calculates RAID parity in software, but there was no way that it should be pegged that much. Because the CPU was constantly used, the NAS would not enter into any power-saving modes when not in use.
After futher investigation I discovered what was causing the problem, and how to resolve it. I clicked on the CPU graph to open up a sub-window that contained information about all the running processes. It appeared that the "convert" command was using up 99% of the CPU's time.