3 gpus pcie lanes

[iancomputerman]

hello, i don't understand why this motherboard:
https://www.gigabyte.com/Motherboard/GA-Z270X-Gaming-K7-rev-10#sp
says that 3 gpus work in
x8 + x8 + x4
if the cpu can only provide 16 pcie lanes NOT 20

 

[samer.forums]

it uses the 4 lanes from the chipset . and it is not recommended to use , becuase those x4 lanes will be shared with the SSD and harddisk and USB ports from the chipset as well .