Hi,
I am using I7-8700K CPU (running at 4.9GHz), mobo is Gigabyte Z370-HD3P. Both GPU's are o-clocked by +150 and memory by +1000.
Both video cards are installed in PCIEx16 sockets, not in risers, the first produces ca 520 H/s, the second ca 430 H/s.
In 1x risers I saw no more than 230 H/s per card.
I tried it just for fun on my work PC, because ROI of such rig is too long .
I think that on an ordinary rig there will be about 200-250 hashes from each card.