The cards are backwards compatible, it will just run at pcie 2.0 which won't make a huge difference anyway.
I would suggest updating your bios prior to installing the card though.
actually my biggest questio is the PCIe version. is about the mainboard? or i need to update the BIOS as you said?whats the latest BIOS? because i checked with the live update 5....
yea i know that.. the difference on the Battlefield 3 is only 0.45 betwixt 2.0 and 3.0 version.