I don't have the "flat" cables, but it turns out my old EVGA 850 GS PSU was made by Seasonic and has the same end design. Their PSU cables are mesh sleeved though. It's possible you might need to do some pin-swaps though as I haven't looked up the exact pinout for the x-750 vs the GS. The cables have "NB41" printed on the side of the PSU connector. I have 3 of SATA ones that have 4 SATA connectors on the cable. On visual inspection, the PSU ends are identically patterned for every cable from the EVGA GS vs the x-750.