Hi Everyone, I have a imac27 2012 (NVIDIA GeForce GTX 675MX 1024 MB) and I just bought Dell UltraSharp U2713HM. I want to use dell monitor as second monitor(extended) for my iMac. At the moment I'm using thunderbolt to hdmi converter and connect dell monitor using hdmi cabal. dell monitor support (2560 x 1440) but when I connected dell monitor run at low resolution ( 1080p). can anyone help me to find out how can I use dell monitor also 2560 x 1440 resolution. Thank you.