Some mobs use a 24-pin ATX connector, others still use a 20-pin, most 24 pin can run on 20 pin or vice versa with an adapter or if there is room to let the extra 4 pins hang over the end of the mobo connector (that's the way mine is. Some mobos have a 2x4 power connector or a 2x2 power conector with half the pins being 12V (yellow) and the other half ground (black). I think PCI express are 6-pin connectors. IAC, look at your mobos manual, see what it uses and buy accordingly. If SLI or whatever the ATI thing is video is in your future, buy SLI or ATI certified, if not, fageddaboudit.. The Enhance ENP-5140G or 5150GH from eWiz via Froogle (save a buck or so that way) can cover most any need.
.bh.