Conputer won't start with CPU 8pin cable plugged in

[ashleeeyy]

Hi, not sure if I'm in the right place but hopefully someone will be able to help.

I've just built a new computer and when I turn it on there is continuous beeping (quite slow) and it won't turn on. If, however, I removed the CPU 8 pin cable and turn it on it seems to be running fine (no beeps). Anyone any ideas on what the problem could be and any solutions? Not sure if its a CPU problem or a power supply one. Sorry if this is vague!

Computer specs:

PSU - CX500 500 watt
Motherboard - P67 SLi EVGA
CPU i5 357k

Many thanks.

 

[kelpt]

does it post with its plugged in or just legit nothing happens at all when you hit the power? Do you have graphics card plugged into the board?