How to send signal to external display on 2011 cMBP?

[Iphone4sinwhite]

I am attempting to connect an external display to my early 2011 cMBP pro. I purchased a Cirago branded (not Apple) mini displayport to DVI single link adapter. I tried connecting two monitors through the mini displayport adapter, one with a DVI cable and the other with a VGA cable with VGA/DVI adapter. Nothing appeared on either monitor and the arrangement tab in system preferences>display did not appear. I attempted pressing and holding F5, F6, & F7 and closing the lid but nothing happened. Any thoughts on how I can get an external display to work?

 

[geoffreak]

Displays should automatically be detected in OS X. If you aren't seeing anything on the display, it is quite possible you have a faulty port, adapter, cable, or monitor. Have you tried hooking up the monitors to another machine?

 

[Iphone4sinwhite]

The monitors work correctly when attached to my PC. Maybe it is the miniDP adapter? Is there anyway to verify this?

 

[geoffreak]

You would need to either plug in the adapter to another machine or try another adapter.