2011 Macbook Pro not detecting external display after new Thunderbolt firmware update

In reply to my own post have to say appologies to Apple whose Thunderbold port I used to blame.

Shame on me)

So, what was my problem?

Guess what?

Manhattan DisplayPort to HDMI Adapter !

The point is it's actually do only what it said to do, converts DP to HDMI.

But I for some reason thought it can be used vice versa, to be HDMI to DP converter))

I was wrong.

I bought new one HDMI to DVI adapter and now I HAVE external display!

Thunderbolt works like a charm.

So I'm very satisfied now.

Hi,

I think I have solved the problem, at least, it works for me and so far, is working straight.

With the external monitor unpluged in the minidisplay port, I set the gfxCardStatus to "Discrete", then, I plug the monitor and it's detected. I have tried it several times and it worked. When unplugging the external monitor, I set it to integrated again (because I'm not using the dynamic function). I just did it again, while writing this and it worked.

Weird thing is, once the external monitor is detected and working, if I chose "Detect Screens" from the Sistem Preferences, second monitor shuts down 😁 I think Apple went bi-polar.

I had a similar issue and after reading the posts, was worried that my older circa 2006 dell monitor would not work with my 2011 MacBook air. But I did note something peculiar that might help someone out there.

I read a post about detaching and re-attaching the connection to the monitor. As i attempted this, the screen flickered and showed the wallpaper, but then went blank as I let go of the cable. I noticed that I needed to apply more pressure to the DVI cable going into the monitor. And when I let go, it would disconnect. I had to use a screwdriver to tighen the connection (the first time ever for me with a monitor cable), and it works perfectly now.

So, make sure BOTH ends are as tightly connected as possible and save yourself a headache!