The Seasonic S12II /M12-II 620w psu has a 6pin and 6+2 pin pcie cable. Or did you loose yours? If so, since most ppl who have those units are still using them, I'd suggest you contact Seasonic directly. I'd strongly recommend you not use just any other psu's cables, even if they physically fit the psu connector as pin alignments will be different and will cause a dead short at the gpu.