I agree, the placement of these so called EZ-Plugs makes cable management an absolute pain.
I ended up making my own custom length sleeved cables to keep it looking as neat as I could.
just looking at the Rampage 4 and the plugs are definatly different. You have by the looks a24pin ATX, 4pin normal CPU power as well as an 8pin CPU power as well as a 6 pin VGA power all for the mobo.
I have tried my board with and without the EZ-Plugs connected and could not see ANY Diff (thats with a CPU oc'd to 4.5ghz)
I would be pretty sure that it will be the same with Rampage. that the extra power injection is ONLY used in extreme OC'ing
as the 690's will draw their extra power from their 6 and 8 pin connectors on the cards themselves i highly doubt you will need the 6pin on the board unless OCing the hell out of it.