first time rig said:
This is my last step as I dont know why seasonic's cable labeled pci-express has only 3 pins while the connector on the top right of MSI GTX 1070's has 4 pins. How do I connect it? Also is there a way to stabilize the gpu on both sides? (like I screwed the other side on the case's plate like many others.
You need to clarify - the MSI card needs 6-pin and 8-pin connectors, both of which are provided by the Seasonic PSU.
As for the second question, no there's no need to secure the free-end of the GPU.