Only plug in the cables you need to use.  The other cables can be left in the box.

You only need to plug in what cords you need with a modular Supply. 
24Pin ATX for motherboard, 4/8 pin CPU (1 or 2 depending on your motherboard), and however many you need for your devices. 

I am doing my first PC build and I am using a few tutorials to help guide me through.  I hit a road block when I got to installing the PSU because all the PSU's in the videos have the cords already installed in them but mine just came with the cords in the box.  I have 3 SATAs, 4 VGAs, 2 CPUs, and 2 PATA cords.  Do I plug every last one of them in or do I only need to plug a certain amount in?  It's an EVGA NEX650 G Power Supply.  Thanks

Quick question about my Power Supply