Pcie riser issuies, maybe?

[doubler]

Was looking through the forms and seen a few discussions on this topic, but haven't seen any one saying it affected there speeds. Yesterday I connected two 6970's, in a x16 both directly into the board, and a 290, in a x1 slot, with a x1 to x16 riser cable and the 290 is running slower than either 6970 using md5 and wpa2. Is this normal or do I need to reconfigure my cards for maximum bandwidth?

The riser cable is a ribbon non-powered.