I just got the Galaxy Note 8.0, and looked all over to see if I could do HDMI display output, to mirror the display on a projector, or my Screen using some USB Crash Cart software. I wanted this tablet to become my primary Android tablet, replacing my Acer w/ built-in HDMI out. I eventually found the MHL Cable to go from micro-USB to HDMI.
Bought 3 of them, and tried all three on my Cisco EX90 High-Definition Display. None worked. Contacted Samsung Support - who responded VERY quickly. Tried the unit on different displays (which I should have done from the beginning) - and it worked on all other displays that I tried.
Here are the ones I tried (all purchased from Amazon):
-ETC-EIA2BEGSTA: Samsung Micro USB to HDMI 1080P HDTV Adapter Cable with 5 Pin to 11 Pin Micro-USB adapter for Samsung Galaxy S3, Note 2 and MHL-enabled Smartphones and Tablets
-Cable Matters Gold Plated Premium MHL to HDMI Cable for Samsung Galaxy SIII & Galaxy Note 2 in Black - 6ft
-Micro USB MHL to HDMI Cable HDTV Smart Adapter for Sprint Samsung GALAXY Note 2 II SPH-L900 - Includes a Hard Carrying Case
Hope that helps anyone else who may be searching for an answer.
Aaron