My motherboard is a GA-Z77-D3H, my power supply is a Corsair Builder Series CX500 V2 500W ATX12V v2.3. There is a 24 pin cable coming out of the power supply, and a 24 pin socket for it on the motherboard, but there is also a 4 pin socket on the motherboard and no corresponding 4 pin cable from the power supply. Did I buy the wrong power supply or is the 4 pin socket by the CPU not necesary when you have a 24 pin cable?