When I'm using 4 7950s per rig I find that I can usually get away with only having 2 of the 4 risers be powered. That said, I've decided to get powered risers from now on. Why skimp on the cheapest part in the system?

I've been having good success with these 1x to 16x risers - http://www.ebay.com/itm/261216266308?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649