I purchased 2 new Dell P2415Q, use thunderbolt to display port, and can not get the computer to power on with both monitors turned on and plugged in. I either have to turn off one monitor, or unplug one of the monitors. This is a very frustrating. Any thoughts on how to fix this?
Mac Pro (Late 2013), OS X El Capitan (10.11.4)
Are they connected to different Thunderbolt buses?
no, they are in port 5 & 6
What happens if you connect them to different Thunderbolt buses as this says:
Use multiple displays with your Mac Pro (Late 2013) - Apple Support
Attach displays to different Thunderbolt busses when possible (see the figure below).
Your monitors are 4K and the Mac only support 3 of those and they have to be connected to different TB buses
still does not work. Could this be related to the "monitors will not wake up from sleep mode" issue?
What exactly happens when you try to startup with the two connected?
Does power light light?
Hear startup chime?
anything show on screen?
hear the chime, see the power light, get a glimpse of the Apple icon with the loading bar below it, then darkness except for the mouse cursor. Then a whole lot of nothing.
- Try resetting the SMC and NVRAM/PRAM
Intel-based Macs: Resetting the System Management Controller (SMC)
https://support.apple.com/en-us/HT201295
About NVRAM and PRAM
https://support.apple.com/en-us/HT204063
- Try starting in Safe Mode
OS X: What is Safe Boot, Safe Mode?
https://support.apple.com/en-us/HT201262
- Boot to Recovery and repair the startup disk
OS X: About OS X Recovery - Apple Support
https://support.apple.com/en-us/HT201314
- If it is repairable reinstall the OSX
How to reinstall OS X on your Mac - Apple Support
https://support.apple.com/en-us/HT204904
- If you do not have a backup use disk utility to restore the internal disk to an external disk so you can try to recover data.
Then format the startup disk and do a fresh install of OSX
Mac Pro can not turn on with 2 displays plugged in.
