I need major help guys!. I recently sold my AMD 7950. I left the computer unplugged from power all week until I came back home from work on the weekend. My new GTX 970 Came in the mail. I plugged it in and booted up my Mac Pro. I get boot chime sound everything is working just fine. I can even log in. But there is no screen! everything is black. I tried all ports on card. and yes both 6 pin power plugs are connected. I sent it back hopping it was the card and I picked up a R9 280X on ebay but I have to wait for in the mail. As a photographer I need my computer now so while I wait i decided to pick up a R7 360 for now and noticed that does not work either. Now i Am not sure if theirs is something wrong wit my mac pro! I pressed the Diagnostics button and I get amber 5V STBY light on and a few other green lights. does anybody have any suggestions of what could be going on!!! --- Post Merged, Apr 30, 2016 --- I have tried to both Reset SMC and take 3V battery out and nothing !!