I have followed the instructions, shut down machine, made sure all cabling is fastened correctly, turned on display, connected the adapter, and turned on iMac...nothing. No idea why it won't detect the display...it's an HP, 27" and it supports 2560 X 1440 resolution...?????
Any help will be a big welcome
iMac, OS X Mavericks (10.9.1), Mid 2010 model