Agree with the others.
Make sure you've got a good PSU with at least one 6 pin pcie power connector.
However, I can see that it's a G31 chipset. I've heard of the HD 5xxx series (PCIe 2.1) being incompatible with a PCIe 1.0 motherboard. A BIOS flash might help, but I'm not sure. I've never experienced it, but I have heard of this problem with other members in this forum.
It is backwards compatible, but I don't think the card's is going to run at it's full potential.