i know this is an old thread, but the only reply is wrong and there is no accepted solution
870 and 970 are identical, just like how the 850 and 950 southbridges are identical
they both support sata 6 gbps
i believe the only difference between 8 and 9 series northbridges is hypertransport. 9 series has HT3.1 and 8 series uses HT3