Question MPG MSI Z490 Gaming Plus - Cannot change PCI-E speeds??

[Hayth]

Okay so when I go into the BIOS, go into advanced and PCI settings it only shows one PCI-e and that's PEG0 (the GPU's PCI slot I believe?) - I've uploaded a picture of it. Not much online but someone said "Apparently it is a limitation of that board as it is only able to change PCIE lanes speed from CPU only. " and someone else said you have to do it through another setting using the MB's chipset? Anyways I am confused as hell and would appreciate any help guys.

 

[Hayth]

 

[hotaru.hino]

Why do you need to change the PCIe speed? If it's to match whatever card you're putting in there, PCIe is forwards and backwards compatible.