I just upgrade my gpu from a Nvidia GTX 580 to a GTX 980. I plugged in the power cables and turn on my computer and turned it on normally. I got the screen with the motherboard options then after a few seconds I ended up in a black screen with a flashing white dash on the top left corner. What is wrong? My motherboard is a GIGABYTE Z77X-D3H, running intel i7, windows 7 64-bit, 1000W psu and 16gb RAM. Any help would be appreciated.