I bought 2 new monitors over black friday, and had to wait all weekend for my mini display port to hdmi to get in. The two new monitors can use HDMI, DVI, and VGA. My old monitor uses only DVI and VGA. They're all 1080p if that changes anything. So I get my cable in, and I hook up all 3 monitors and only 2 of them turn on. I have my old one in the center with DVI. The left one hooked up with HDMI to HDMI, and the right one hooked up with mini display port to HDMI. The left and center monitors work, but the right one doesn't. I can unplug the left one, HDMI, and the right one activates, but as soon as I plug the right one back in, it turns off. Can someone explain?