24 pin to 14 pin

Edit: I'm stupid, and the 8 pin was for sata power Hi, so, I have a lenovo thinkcentre m92p with a 280 watt psu and I want to upgrade it to a 450 or 500 watt. The mobo has a 14 pin, an 8 pin, and a 4 pin for the psu. Does the 8 pin need to be plugged in? What is it? I've found adapters that are...