Hello,
Thank you for describing in details, it is useful.
Here is a post where I explain how I reached my following conclusion:
http://www.displaylink.org/forum/sho...36&postcount=6
The issue you are having is with DisplayPort alternate-mode because you're only meeting the problem on the 3rd display and always on HDMI.
When using 2 displays only, you are using DisplayLink only... and you confirm it works correctly.
This is not something DisplayLink can help with as this is not our technology.
Nonetheless, you may wish to try to decrease the refresh rate or resolution to see if that affects the results. You could also try alternative platforms (with DisplayPort alt-mode) and other displays to single out if this is an issue with the platform, the DP-alt mode or linked to a display. This would help you escalate the issue within Dell.
Kind regards,
Alban.