theres not really a preforamce increase as they are ATA66/100 cables. Same as your standard flat ribbion ones. However they do allow for better air flow and hence possibly better cpu and case temps! They are also nice to work with - if you've tried to twist a flat ribbion to connect say 2 hard drives, it's a pain. With the these since there round it's nothing to put 1 or even 2 twists into these cables. They even look nice if you have a case window and with the right light ( black light with white round cables!! ). I'd go for them, wait I did