MacBook Pro external monitors not working So I was just using my MacBook Pro with an external display last night and it was working beautifully. For some reason, though, today it isn't working at all. I have a TB-to-HDMI cable which is hooked up to an HDMI-to-DVI adapter. I have just tried it on an HDMI tv and have gotten nothing except a "Not supported mode" and a mouse flicker. By the way, it's not just the tv and monitors not working. In the System Preferences it doesn't show any other displays or an option to extend or mirror like usual. I will be getting another cable tomorrow to see if that is the problem.

An important question that I have and what I am most concerned about is that I have gfxCardStatus installed and when I tried using my external display today I forgot to turn it off of "Integrated only". Do you think that could have broken something since external displays require the other GPU? Sometimes when I plug in the cord gfxCardStatus shows it going into the AMD GPU but then if I look under dependencies it says "None" (it usually said "Extended Display").

On very very rare occasions when I unplug the cord I will get a blue screen flash like it is changing display settings.

Some things I have tried:


Wiggling cord
Messing around with gfxCardStatus (even turning it off)
Changing settings in Energy Saver PrefPane
Clicked on "Detect Displays" many times
Resetting PRAM
Resetting SMC


Another thing is that I just recently got my logic board replaced so I wouldn't think that would be the case but unfortunately their 30-day repair warranty is up.

One more thing that I have found while scouring the internet is I came across a picture of someones System Report for Graphics and at the bottom of the read-out it says: Display Connector: Status: No Display Connected but mine doesn't say that (I don't know if it used to either).

What are some of your thoughts? I am really hoping it is just the cord.

EDIT: Just tried my Xbox into my HDMI-DVI adapter with the monitor and it worked so that rules that out. It has to either be my cord or my computer
You need to switch to discrete graphics in gfxCardStatus (or dynamic switching) for external display support. Also make sure you're running the latest version by running “Check for Updates…”. (Your cable is likely just fine.)