It's a split 8pin connector, it is split as there are still some motherboards that only utilize the 4pin socket. You do need to have the 8 pin connector, though for your motherboard whether it be single 8 pin or 4 + 4 connector.
You'd need to specify your other hardware for replies to give you a proper assumption. You might be using SLI or CROSSFIRE (two video cards), Sound card, 2 or more hdd's blu-ray CD/DVD drive, etc.. Also, specify your OS and type.
All spces hould include Brand, Model, verison, speed, watts, serial numbers, where applicable.
Usually, the Corsair TX750 is more than adequate for most rigs.