I have a 27" 1440P 144Hz monitor (Dell S2716DG) and an old MacBook Air (2012). With a mini-displayport to HDMI input into the monitor, only 1080P is offered in the Display settings. What cable and or accessory do I need to purchase to allow for 1440P output from this laptop? Do I just need a Mini DisplayPort to DisplayPort cable? http://www.staples.ca/en/StarTechco...Adapter-Cable-M-M/product_162364_1-CA_1_20001 Why can't Mini DisplayPort to HDMI output anything past 1080P?