Another problem I encountered with 975XBX2 was that after installing the Geforce 8800 GTS card (which takes 2 slots) I have no access to the motherboard front audio panel connector anymore. My Armor case has USB and audio connectors on top and would have liked to use them.
I could move the video card to a different PCIe slot, but the first slot is the only one which supports electrical x16.
It's a shame that nobody thought of that, considering that 2 slots video cards aren't quite new.