First, what PSU do you have? You don't want to go connecting a GPU to an underpowered or low quality PSU.
The AMD cards can actually run with just one 8-pin connected (which is the 6+2-pin) even if it has an 8-pin + 6-pin.
*Okay, Corsair RM650i is good quality. It should have an extra PCIe cable for you to connect all cables. It's modular, so the extra cable may be elsewhere in a box or something.
First, what PSU do you have? You don't want to go connecting a GPU to an underpowered or low quality PSU.
The AMD cards can actually run with just one 8-pin connected (which is the 6+2-pin) even if it has an 8-pin + 6-pin.
*Okay, Corsair RM650i is good quality. It should have an extra PCIe cable for you to connect all cables. It's modular, so the extra cable may be elsewhere in a box or something.