Will my computer run better if i get a 24 pin powersuply instead of using my 20 pin on my 24 pin board?

DiabloTek / 400-Watt / ATX / Dual 80mm Fan / 24-Pin / SATA Ready / Power Supply. Its only 19 bucks, I know i sould get one that has 700-watts like my old one but its only 20 pin