Total hashrate is 3 Mh / s and I have 1.7 Mh/s (1.3 Mh/s on the one rig + 0.4 Mh/s on the second rig). Yet, for round 2 hours I am not found nor one block. How it is possible?

Time of mining is gone, at least for now. Can't even find as good as nothing with my 10500 kh/s. Better mine something else.