I interpreted it as it stated Gen3 (16, 8, 8, 8), Gen2 (1, 1, 1) so I assumed them to be in order this way. But once I read Guru3D review I found this Slot 1/3/5/7 are PCie Gen 3 and thus have double bandwidth. 1 and 5 support Gen 3 x16. When the four slots are utilized you'll jump back to x8 mode, yet at Gen 3 that's the same as PCie Gen 2 in x16 mode bandwidth wise.
The three PCIe Gen 2 slots are 2, 4 and 6 and get their bandwidth from an added PLX PEX8608 IC chip.
CHECK OUT MY BUILD LOG
It's going underwater