[NAME] The bottom graph is the disk transfer rate, the top graph is the active time. The active time looks to be periodic but the percentage of time the disk is processing read or write requests is very small. You should look at the Processes tab in Task Manager to see if you can determine what processes the disk activity corresponds to. Since the percentage of disk activity is small determining the process may be difficult. The other thing you could do is in the Startup tab, you could right-click on each of the Startup apps and disable them one at a time to determine if one of them is the cause of the disk activity. You can right-click on the Startup app to re-enable it if it is not the cause of the disk activity. 
This is my first computer with a SSD. Yes, I’m a bit behind the times. I’ve noticed the disk light (on the back by the speaker plug) flashing constantly with no known activity on the system. At first I thought it was a code of some sort, but now just think it’s activity of some sort. The flashing is not consistent but it’s a few times every 10 seconds - as a guess. any ideas in this?  Thanks
XPS 8940, SSD light very active