Question Pc won't boot

[Chris_White]

if i insert the graphics card in the x16 slot the pc wont start. But when it is in the x4 slot it will work
i also switched motherboard, the graphics card works on the old motherboard on the x16 slot fine

 

[rgd1101]

full system spec? include make and model of the psu

 

[Chris_White]

full system spec? include make and model of the psu

CPU: Ryzen 5 2600
MB: MSI B450M Mortar
Ram: HyperX ddr4 16GB
GPU: MSI GTX 960
PSU: Coolermaster Silent Pro 500w