Just installed a new GTX 780 ti Asus card and was quite surprised by very noticeable high pitch coil whine. Fortunately I have second machine so I could rule out the PSU. The sound is similar to the link below. I wasn't expecting any coil whine, but I am not sure what others have experienced?
https://www.youtube.com/watch?v=3PMcmOxZ7_0
PSU: 750W Seasonic X-Series
2nd PSU: XFX 750
https://www.youtube.com/watch?v=3PMcmOxZ7_0
PSU: 750W Seasonic X-Series
2nd PSU: XFX 750