Hi, Can anyone here offer my a guess as to the cause of my recent computer issues. I have a 2009 Mac Pro on 10.10.5 I recently like (2 weeks ago) got a used reference GTX 980 (not flashed) to drive my new displays (both 4k resolution). This is an upgrade from the GT 120. I don't know if this is a graphics issue but I just want to state the changes I recently made. As of late, my computer is having problems. Often, after some use or little, one screen (connected by DP cable) will turn green or black and the other (connected by HDMI) will stay on but freeze but I can still control the mouse cursor which turns to a beach ball where I can do anything. Shortly, this second screen will freeze and I'll have to restart the computer. I could be doing nothing but browsing the web using chrome with two tabs open and it happens. Any guess as to why? Any tools that I can use to diagnose the problem? I am using console to help but I admit that I am not very experienced with this. I will happily provide more info to anyone willing to assist. Thank you for your time. It is greatly appreciated.