Question A Z390 motherboard should switch to x8/x8 PCI with second graphics card, right?

[nc3d]

When I add a second, identical 2080ti graphics card and Nvlink to my Asrock z390 system, the cards show up in x16/x4 mode, not x8/x8 mode as expected, so I get no SLI.

The only other thing I have installed on the motherboard is an .M2 SSD which I've tried in two different slots.

I've tried doing a clean install of the drivers, but this seems like a hardware issue, right? (The motherboard should put the slots in x8 mode when two cards are installed.) Is there some way to force x8/x8 mode?

Windows 10
32 GB RAM
2x EVGA RTX 2080ti hybrid
EVGA NVLINK bridge
Asrock z390 Phantom 4 motherboard
Intel M2 SSD
1TB SATA HDD

Thanks!
-Donald

 

[rgd1101]

because it not sli supported, only crossfire supported

is right on the spec
https://www.asrock.com/mb/Intel/Z390 Phantom Gaming 4/index.asp#Specification
2 x PCI Express 3.0 x16 Slots (PCIE2/PCIE4: single at x16 (PCIE2); dual at x16 (PCIE2) / x4 (PCIE4))


you need a phantom 6 or higher

 

[nc3d]

Thank you!
SLI installation instructions are in the manual so I assume it was enabled on the board!