185      iPhone_iPad_Mac_手機_平板_蘋果apple

MacBook Pro external display only works with HDMI3

Hi Everyone! Here's my problem, I'd really appreciate if someone could help me.

CONTEXT

I've used my MacBook Pro (late 2011 with up-to-date Sierra) with an LG IPS LED 27" monitor at the office and a Samsung SmartTV at home both connected to port HDMI2 and never had a problem. However, recently I connected a new cable box to the Samsung's port HDMI2 so I plugged the MacBook to HDMI3.

PROBLEM

The next day when I plugged the MacBook back to the LG monitor it didn't work. The OSX detects the LG monitor, I can see it in the System Preference, even the model... everything but the screen is completely black. I thought it was the monitor so I tested it with another computer and it worked! Then I thought it was the cable, so I tested the same cable and it worked.

At this point I was a bit lost so I plugged the MacBook back to the Samsung TV using port HDMI3 with the same cable and it worked but surprisingly when I plugged it to Samsung's port HDMI2 the TV went black just like the monitor. Crazy! The MacBook is only working with HDMI3, the problem is that my LG monitor only has one HDMI port (HDMI2).

FAILED ATTEMPTS

So far I've tried the following and none had solved the problem:

1. All steps at Get help with video issues on external displays connected to your Mac - Apple Support: Fail
2. Different cable: Fail
3. Reset NVRAM and SMC: Fail
4. Reinstalled Sierra: Fail
5. Update to High Sierra: Fail

As you can see I've tried most of the recommended steps and yet my MacBook external display only works if connected to port HDMI3.

Please help!

最後更新：2017-09-26 22:21:42

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