MBP retina 15'' with dell ultrasharp u2713hm

LMHKI,

Make sure the Display Port end is plugged into the "Display Port IN" on your monitor and not the "Display Port OUT". I've not looked closely enough and plugged the cable into the DP OUT once or twice with my U2414H.

If it is, make sure that DP is the input your monitor is set to use. If all that's working, I would try resetting the monitor from the On Screen Display, putting it back to factory defaults.

If that still doesn't work, it's possible the Dell cable isn't up to the task any more and you might want to look at an Accell or StartTech mDP to DP cable that's certified for Display Port 1.2. I purchased the Accell - http://www.amazon.com/gp/product/B00A7R9I22?psc=1&redirect=true&ref_=oh_aui_deta ilpage_o00_s00

Hope this helps.

First, make sure you buy a Thunderbolt drive that has two TB connectors on it for daisy chaining. Connect it to the computer first. Then connect your display. Your display, ANY display, will always be the last in the Thunderbolt daisy chain because the only signals that can pass over the connect to the display are the Display Port (video) signals.

Hope this helps.