Urgent GPU problem

[PLEASE TELL ME]

When I plug in my GPU my cpu fan doesn't spin and light on my MB and GPU start flashing.
How do I fix this? My GPU is a EVGA gtx 1080 FTW, my MB is a GIGABYTE H110-S2HP and my power supply is a Corsair VS650

 

[spat55]

Do you have the PCI-E cables connected to the GPU and the CPU power cables plugged into the CPU power header? Have you updated the motherboard BIOS without the GPU in it?