The card is PCIe 2.1, not 2.0. Unless Biostar has an update to provide PCIe 2.1 compatibility, it will not work on that motherboard.
Consult these two other threads wherein the same situation was experienced and the same conclusion was drawn.http://www.tomshardware.com/forum/285668-33-problem-radeon-5670http://www.tomshardware.com/forum/285613-33-radeon-5770-displaying
The simple fact is that PCIe 1.0 and 1.0a need a proper update from the motherboard manufacturer to provide compatibility support for PCIe 2.1 cards. If they don't have such an update, then that's that. Per my discussion with a representative from XFX:
"That is just the way that it is. The motherboard manufacturer didn't implement the proper support before discontinuing support for the product. Some of them did and some did not. It happens when new standards come out.
My advice: Get a 4000-series card or something from the nVidia camp.