Dual Cinema Displays on PowerMac G5

I'm trying to hook up 2 - 20" Acrylic Cinema Displays to a PowerMac G5 with nVIDIA Quadro FX 4500 card. The problem is the connectors on the monitor cables are slightly to thick and I can't align them to the connectors on the card. There's no problem with the new displays, there connectors are more streamlined. Has anyone run into this? I'm hoping to find a short monitor extension cable that has a slimmer case. Any other ideas?

Older Cinema Displays used ADC connectors, not VGA or DVI. Could this be the problem?

I should have stated in the original post that I'm using the correct adapter. One at a time they will connect and work. If I try to hook them both up the size of the outer shell on the cable connector makes it physically impossible to fit both onto the card.

Per your thought, I would recommend going out and buying some short cable extenders, where the plugs at each end are thinner. I have bought cables at CablesToGo in the past, and they seem a good source. See http://www.cablestogo.com.