I want to connect my MBP 2015 to my external monitor http://www.asus.com/Monitors/VS239H/ through HDMI port. I found out that by using AMD Radeon, my MBP's battery is draining fast and the fan is noisy. So, I try to use gfxCardStatus to use Intel Iris Only.

But, it just doesn't connect at all. The external monitor doesn't detect my MBP (it says HDMI No Signal). My MBP also doesn't detect my external monitor.

Why does it happen? And how can I do it?

1 Answer 1


Are you using any kind of adapters to connect the monitor or is it straight HDMI to HDMI connection? I had troubles with non-apple adapters – the simply dind't worked for me...

You can make 2 things to diagnose the issue I can think of:

  • boot into linux (make a usb from ubuntu with unetbootin)and check if it works in linux – if it does it's a software issue (i guess), meaning some kind of hack is necessary

  • check your system.log by opening the Console.app or by tailing it in terminal with tail -f /var/log/system.log, also take a look if sudo dmesg got anything useful to say.

When you got the console or terminal open – just connect/disconnect the monitor and check if you get any kind of log activity from it, that should at least give you some idea if the hardware reacts on the display when Intel HDxxxx is used for graphics.

I would first check the syslog and then check the setup in Ubuntu 15.10, grab the latest Ubuntu iso file from here: http://cdimage.ubuntu.com/daily-live/current/wily-desktop-amd64.iso

  • Sadly, I use HDMI to HDMI connection. Oct 6, 2015 at 23:58
  • still, check the log output for some hints when connecting/disconnecting
    – PJJ
    Oct 7, 2015 at 0:28
  • found anything in the logs when connecting/reconnecting?
    – PJJ
    Oct 7, 2015 at 17:02
  • haven;t had time to check the logs, been busy in projects. I hope I can check it in the weekend. I will post it here after I do that. Thanks :) Oct 7, 2015 at 23:40
  • I have check it, see it here : gist.github.com/ismailsunni/b5d98e174e041caf3e17 I didn't get the log in first time, but I plug n un-plug the HDMI, then something is coming out. Not working still though. Oct 7, 2015 at 23:47

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