I do not think it is SLI compatible. I have seen old Dell gaming pc that uses nvidia chipset which natively supports SLI. the two PCIex16 physical slots in 9020 mt are not the same.  The blue one and black one.  Blue one is wired x16, the black one at bottom of mobo is wired x4.  The x4 wired slot can be used for PCIe nvme ssd etc add in card. The only x16 wired slot is for video card.
Just wondering if the 9020 MT is SLI compatible? If not, just want to understand why as the Mobo has 2 PCI-e slots.   Thanks!
Is the Optiplex 9020 MT SLI Compatible?