Yes, Elgato Thunderbolt™ 2 Dock supports 4K video and Ultra HD TVs, but the resolution and frame rate (Hz) will depend on the interface and your computer.
4K With A HDMI Display
HDMI output from Elgato Thunderbolt™ 2 Dock is up to 4096x2160 at 24Hz, or 3840x2160 at 30Hz.
4K With A Thunderbolt Display
Higher frame rates than HDMI are available over the Thunderbolt™ 2 port.
To get 4K 60Hz video, you will need a computer that supports it.
These include:
- MacBook Pro (Retina, Late 2013 and later)
- Mac Pro (Late 2013)
- iMac (27-inch, Late 2013 and later)
The Mac mini (Late 2014) does not support 4K 60Hz video.
To find out more about 4K support for Macs, please see this article at Apple:
http://support.apple.com/en-us/HT202856
Video output format and frame rate may be limited by host capabilities.
4K With A DisplayPort Display
Higher frame rates than HDMI are available over Mini DisplayPort, via the Thunderbolt™ 2 port.
To get 4K 60Hz video, you will need a computer that supports it.
These include:
- MacBook Pro (Retina, Late 2013 and later)
- Mac Pro (Late 2013)
- iMac (27-inch, Late 2013 and later)
The Mac mini (Late 2014) does not support 4K 60Hz video.
To find out more about 4K support for Macs, please see this article at Apple:
http://support.apple.com/en-us/HT202856
Video output format and frame rate may be limited by host capabilities.
Multiple Displays
Elgato Thunderbolt™ 2 Dock can only support multiple displays in certain ways.
See this article for very important details about the limitations:
How many displays can be used with Elgato Thunderbolt™ 2 Dock?
Notes About 4K Support
The resolutions and frequencies that can be used depend on both the graphics card in your Mac and the display itself.
To find the specifications of the graphics card in your Mac, you can use the links below:
http://www.everymac.com/ultimate-mac-lookup/
http://www.mactracker.ca/
Also check the user manual of your display to see what resolutions and frequencies it supports.
Once you have connected the display to the HDMI port on the Elgato Thunderbolt™ 2 Dock, you can find out the frequencies and resolutions supported by your Mac and your display by going to System Preferences > Displays window. To view all the resolutions supported by your Mac, press the Option key and then press the Scaled option.