I have an experimental rig asus prime z-370A + i3-8100
If you include 3 1050ti cards through risers into 3 GEN3 slots (3 16x - GEN3), you get the result: 150, 150, 250, if you connect 2 cards to GEN3, and third in PIC-E 1x, you get 150, 250, 250.

0-290.1 1-233.5 Total: 523.7 H/s  2018/06/03 20:20:03 1 - Yay, solution found!
0-309.1 1-245.0 Total: 554.0 H/s  2018/06/03 20:21:11 1 - Yay, solution found! - 2x1050ti Intel(R) Pentium(R) CPU G4400 @ 3.30GHz PCI-E 16x GEN3 without raisers