B450 Tomahawk Max PCI_E4 x16 physical slot only capable of x4?

[camjocotem]

Hey so I bought some 10GB NICs thinking:

"I have two x16 slots on my mobo, I should be able to stick my NIC into the second slot and have them both run at x8" (which is what I'm used to seeing)

But if what I'm seeing is right then the second slot is only capable of x4? If so what is the point in having the physical x16 slot there? :S

 

"Manual" tab here for reference https://www.msi.com/Motherboard/support/B450-TOMAHAWK-MAX#down-bios

or direct here

Mobo manual

[Eigenvektor]

Probably so it can physically take a x16 card. In the specs, it says this:
https://www.msi.com/Motherboard/B450-TOMAHAWK-MAX/Specification

 

1 x PCIe 2.0 x16 slot (PCI_E4, supports x4 mode)¹

PCI_E4 will run x2 speed when installing devices in PCI_E2/ PCI_E3 slot.

 

~edit: It may also simply be cheaper to manufacture when using the same type of slot everywhere, regardless of the PCIe connection.

[camjocotem]

@Eigenvektor I guess it could be a cost thing. 

A bit misleading that a physical slot only has at max 1/4 of the bandwidth you would assume it could have 

[camjocotem]

_{Any idea if it would still work?}

_{(Granted it would be at a bottleneck?)} 

According to the specs x4 should provide enough bandwidth for a 10Gb NIC (just about!) but the card itself specified it wanted x8