The power supply unit is supplied with the internal cables as it is a fully modular model. This means that you can only connect the cables that you really need for your system. The exact selection and number of cables can be found in the supplied packing list.

Yes, there are enough. You can use one of the two Dual PCIe 8-Pin (6+2) cable and a single PCIe 8-Pin (6+2) cable to connect a 3x 8-Pin GPU.