PC note loading up windows when using GPU

[I2eaper HD]

HI guys

i have just finished building my pc and when i try and boot it up with my GTX 970 it doesnt show anything on the monitor even if i have the HDMI plugged into the motherboard, but when i remove my GPU from the motherboard it boots up, what should i do?

 

[PIEapple]

Have you connect the GPU power pin?