What are your full systems specs, a motherboard won't give us full details. Without more info all I can suggest is a 5970 as it is the best board overall but you may run into issues with ram or cpu.
As long as your motherboard has pcie slot then you can use almost ANY pcie card.
Agree with deweycd, we need more info here, tell us your FULL specs:
CPU-RAM-PSU-Monitor-Budget?