Probably an engineering test to see how well the GPU performs with older CPU and south bridge hardware. I doubt this is the actual real performance from the GPU itself. PCI-e 2.0 x16 is a decent jump from PCI-e 3.0 x16 in terms of bandwidth. I'd expect more test leakage like this with the newer hardware AMD is releasing at Computex for real testing purposes. For actual data, that is.