Video Card Shenanigans

Alright. I have the HD Radeon 5750, and I recently purchased a new power supply to go along with it. It's a 650w, and can run it fine along with my low end processor. I read online recently (can't remember where) that if your video card has a power cable that it may be sharing with something else that it may affect the video cards performance.

I understand how that may work, but I wanted to see some clarification. I checked my cables today and noticed I had my card sharing a cable with my dvd drive, and unhooked the dvd drive and changed it to another cable. I feel like there is a performance increase, but I'm not positive if it is just me thinking that there should be or if it actually did increase in performance. Anyone give any confirmation on that?