7920, 2 CPUs, wmic SYSTEMSLOT instruction, not correct BusNumber

Background: I want to get the slot number in which the GPU board is inserted

I am using the "wmic SYSTEMSLOT get /value" instruction on a Dell 5820 Windows 10 64bit to get the BusNumber value. The value is correct, the correct value where you put it, 65535 where you didn't put it. But in the same way, the result is incorrect on Dell 7920 Windows 10 64bit. The BusNumber value of all obtained slots is 65535.

Is there any workaround for this issue?

In addition, I tried with three 7920 PCs. 1 unit (only 1 CPU) is OK, 2 units (2 CPUs) is NG.