System pref does not detect second monitor (HDMI), however mirrors video to it

[rahalb]

Hi guys, not sure if anyone has had experience with this and can help me out. I have a HD5670 which works well and is properly detected by the OS on Clover running El Capitan . The problem however is the HDMI output:

1. Booting with both the HDMI and DVI plugged in together works well, but I am limited to mirrored display (have no option to extend it), and system preferences does not detect another display is connected even though it is mirroring fine.
2. Booting with just the HDMI plugged in causes the monitor to turn off right before the login screen displaying the bios screen and everything properly before that. If I however plug in my DVI connection, both screens will turn on but again, will only show the DVI connection in system preferences.

3. Because it is not detecting another display, I do not have the option for HDMI audio output.

Any help would be greatly appreciated. Thank you

 

[n3oNLit3]

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[rahalb]

Sorry about that, and thank you for your patience. I have updated my information.

 

[Essystyle]

I am having a very similar issue. Mirroring on boot up but one monitor gets all pixely and weird once i get to desktop. No detection of a second monitor. I use onboard HD4600 graphics though. One connected to DVI and one to HDMI. Both works fine alone. Let me know if you figure out something useful.