Whats the best graphics card which only draws power from the pci slot?
What is the best graphics card which gets all its power from the pci-express slot?
More aboutwhats graphics card draws power slot
HD 5670 or the newer HD 6670 which is about 10% faster than the HD 5670.
But are you sure your power supply is powerful enough even for those low power cards? What is the make and model of your power supply unit? You might have to open your case and look on the label on the PSU.