Dual RTX6000 ADA on gaming motherboard


We would like to use 2x RTX6000 ADA on a gaming motherboard (MSI MEG Z790 ACE). It will boot with 1x RTX6000 ADA in any slot, but the motherboard returns a D4 error code when 2x RTX6000 ADA are present in any slot combinations.

We have no problem with 2X RTX4090 on the same motherboard (with a PCIe extender cable).

We prefer to use an i9 motherboard for the fastest single core performance. We have updated to the latest BIOS, and tried different combinations of BIOS PCI settings to no avail. Any help is appreciated.