MSI PRO Z790-P WIFI DDR4 Manuel D'utilisation page 30

PCI_E1~4: PCIe Expansion Slots
⚠
Important
If you install a large and heavy graphics card, you need to use a tool such as MSI
∙
Graphics Card Bolster to support its weight to prevent deformation of the slot.
∙ For a single PCIe x16 expansion card installation with optimum performance, using
the PCI_E1 slot is recommended.
When adding or removing expansion cards, always turn off the power supply and
∙
unplug the power supply power cable from the power outlet. Read the expansion
card's documentation to check for any necessary additional hardware or software
changes.
PCI_E1: PCIe 5.0 x16 (From CPU)
PCI_E2: PCIe 3.0 x1 (From Z790 chipset)
PCI_E3: PCIe 4.0 x4 (From Z790 chipset)
PCI_E4: PCIe 3.0 x1 (From Z790 chipset)
28