So i have a card that uses 1 6pin cable but im upgrading to the one that uses 2(being sent without additional cables though) and i found an old 6pin cable that has 2 connection points for PSU.. So, what gives? One that im using has only one, why does this one have 2? Is it for better efficiency? And do i need to plug them both in the PSU for it to work or just 1?