Not too many differences between the two, the GA-F2A78M-D3H supports eyefinity, I don't see that listed on the GA-F2A88XM-D3H, however if you aren't too concerned with supporting six monitors I'd go with the GA-F2A88XM-D3H, as it has 8 sata 6Gb/s connections whereas the GA-F2A78M-D3H only has...