Try taking out the gtx 960 and then plug directly into the motherboard, this will tell you if its the graphics card or not.
If it is the graphics card the best thing to do would be to check all your drivers are up to date first and update any that are out dated. If that doesn't work try a port on the card for example DVI, HDMI or the Display port; as the pins/contact pads could be damaged.
Hope that helps at least