Ok, I re-set all the power connections, found a description of how to tell which direction to place the system panel connections, and tried it again - I now have a green LED and power when I hit the power button. However, I don't get any system beeps, and I have no video.
I have a Radeon HD3870x2, I plugged in the 6-pin power connection. I don't have an 8-pin power connector that will fit the 8-pin connector on the video card, could this be a problem? The red LED on the card is lit, however, so I think it has power too.
Thanks again in advance!