"error initializing pci express slot 1"

I just installed a brand new PSU and started my PC for the first time in months and when i start it up it gives me the message "error initializing pci express slot 1" and when i hit f1 to continue it gives me the normal Windows startup screen suddenly stops and returns me to the message. I'm guessing it has something to do with my graphics card. 

SPECS 
Dell Optiplex 960 MT
Windows 7 64 bit
EVGA GTX 1050 SC 2GB
4GB RAM 
EVGA 400W PSU