I have a htpc setup consisting of my desktop with 1 Intel Core 2 Duo E4500 @ 2.2Ghz running Windows 7 Home Premium 64 bit with 4GB RAM and 1 MSI Nvidia 9600GT video card connected to a 47 inch LCD TV over HDMI and to a 24 inch LCD monitor over DVI. I have XBMC on this desktop serving the media content. The desktop contains 2 hardrives connected by SATA/300, each partitioned into 2 partitions. The 1st partition on first drive contains the OS and XBMC and the 1st and 2nd partitions on the second drive contain the media files.
I have noticed some stuttering on the screen when running 720p video files. This is not direct off the disc playback of BluRay; rather its playback of compressed video files from the harddisk. The stuttering is not always present - it seems to happen only when there is fast action (like camera panning quickly) - though I have not been able to determine a fixed pattern for sure.
CPU - I have looked at the CPU usage when this stuttering is visible and the usage at that time and in general throughout the playback is typically below 20% - so it does not seem to be the CPU getting overloaded.
I know the cause of the stuttering could be anywhere, I need help in figuring out where to start looking into and resolving the issue.