hi there i just got this to play my ps3 or 360 on but i plug it in and pis "cmd + F2" but nothing happens
please help me i have no idea on what im doing wrong
Looks like that is a mDP to HDMI adapter, meaning that you can use that to connect you iMac to an external monitor with HDMI. What you need is an HDMI to mDP adapter which lets you to connect a device equipped with HDMI to the iMac. You need something like this
Are you trying to play your PS3 on your iMac screen? Then you'll need a converter box I believe, as the adapter you have is probably M-DP->HDMI, rather than the other way around. Your local Apple Store should have the converter box.
You need this. Cheapest you're going to get it at that does what you need to do.
Mine just came in today from the same seller and works great. Read the manual and change the resolution on the item that you're getting the vid source from i.e. your xbox.