I recently put a build together and suffered a similar problem with my GTX970, can you tell me the rest of your build?
To get mine working I played around with the cables, keep trying different ports from your GPU to monitor, I think in the mine worked with DVI from GPU to monitor, install windows, install the drivers, update the drivers to the latest and then stick HDMI or DP whatever you were using back in
Hope this helps, but still might be handy to know the rest of your build including your monitor.