500W+ power supply for Dell Optiplex 980?

I've got an Dell Optiplex 980 that I would like to install a better video card into. I have a Quad DVI ATi card to install. The video card requires 2 6-pin PCIx power connectors, so I need a larger power supply. No big deal right? Well the Dell motherboard has some 24-pin power connector that is about 25% smaller than a standard ATX power connector. Dell calls it a 'Micro Power Connector'. Is this just some proprietary BS? Or is there some new standard for motherboard power? Anyone seen an adapter to get a regular ATX PS in there?