Wow. It seems no one can clarify the function and interrelation of these services or their effect on DPC latency.
I still have no idea what particular DZ68BC features I have disabled. Or are they still functional but not accessible from the OS?
With respect to the latency spikes I was experiencing, it seems to be caused by an interaction between the Intel Desktop Utilities (IDU) program and the Intel(R) Rapid Storage Technology (RST) Driver (RAID driver). Uninstalling IDU seems to prevent the problem and reduce latency to an acceptable minimum.
5. Known Issues
ISSUE-1 -- An issue has been reported that indicates the Intel Desktop Utilities (IDU) program can occasionally negatively impact audio/video streaming. In this case, users may see dropped video frames and/or glitches in audio playback. These issues only occur when Intel(R) Rapid Storage Technology (RST) is also being used to manage RAID arrays and/or array/drive caching.
STATUS - Under investigation. Work is in progress on a fix and will be included in a subsequent release of Intel(R) RST.
WORKAROUND - No workaround is currently available. Until such time as a release of Intel(R) RST becomes available that addresses this issue, users may choose to uninstall IDU. This will not necessarily prevent audio/video stuttering from occurring, however, it may only lower the occurrence rate.