If you go to Energy Saver in System Preferences, you can select the 'Power Adapter' option, then move the slider to when you want the display to turn off when no activity is detected.
You can also go to Mission Control in System Preferences and setup a hot corner to 'Put Display to Sleep' which is a little different than having the display turn off without sleep mode.
Thanks! Will give that a try tonight. Will probably also reset my SMC and see if that solves the random wake issue.
I just received my 5k. Laptop is the 13 3.3/16/512. I have a Belkin (the one sold by apple) usb-c to ethernet adaptor. When plugged into the 5k screen, i'm getting about 1/2 bandwidth. When plugging into the laptop directly, getting full. See iperf results below:
This appears to be a driver issue. See post below by @maxb that should solve the issue.
Update on Realtek based (Anker, Belking, Cable Matters, Monoprice, etc.) USB-C Ethernet Adapter not getting full speed when connected to the LG5k monitor : the problem is driver related
The driver built-in OSX seams to be the problem
The driver found on Ankers website seams to make the adapter able to go full speed. For now, I'd suggest anyone using one of these adapters to download and install the driver.
I should probably report the bug to Apple so they can fix it in next OS upgrade.