Intel S5520SC Motherboard Issue

I have a system based on Intel's S5520SC motherboard - Dual Xeon 5580, 12 GB RAM, Radeon 4870, etc. I'm running Window 7 Ultimate RTM 64-bit and having all kinds of performance problems. One of the more strange things is that even when there is really nothing running on my system the task Manager shows activity on all 16 threads

Aside from the first thread, all the rest of the threads show busy, then slowly ramp down to no activity, and then jump back to busy again. This repeats every minute or so.

When I go to the Processes tab in the Task Manager there are no processes using any CPU.

I suspect this may be related to the performance problems I am having. For example just typing this message I get pauses ever couple of seconds for a second or so. Other applications have similar pauses in them. Often when I'm playing audio there are pauses every few seconds or so.

Does anyone have any ideas on what may be going on with my system.