wim-bart wrote:
Nope, I did it and it is running at x8. And I was hoping it runs on x16. Because the temps are better of all my components, it is really great to have it there. But it runs at x8 and not x16. It might not be a problem because it is a PCIe 4.0 card but not what i hoped for. So ASUS has another product what is not good. For me it feels defective because with a 3900X = Zen 2 it should support at least 2 times a x16 configuration. It also says that on the product page of the board.

The manual is not really helpful in this. In the manual both slotrs are as x16 with x16 wired. The manual says:
Slot 1 = used, Slot 2 = no used: slot 1 = x16, slot 2 = n/a
Slot 1 = used, Slot 2 = used: slot 1 = x8, slot 2 = x8

But no config for Slot 1 = empty, slot 2 = used:

On the technical specifications, and my choice to buy this board states:


What is for me, when using a 3rd Gen AMD Ryzen (what i am using) there are the following slots:
2 x PCIe 4.0 x16, either in x16 modus or when used both in x8 modus
3 x PCIe 4.0 x1
1 x Pcie 4.0 x16 operating in x4.

So when no video card is used in Slot 1, the second Slot should be working in x16 modus. So it does not work in x16 modus, so it is defective, or the board is not defective, but the specifications on what I did buy the board do not meet the reality and are misleading.