MSI X299 GAMING M7 ACK Présentation Rapide page 30

Multiple graphics cards installation recommendation
PCI_E1
For 44- & 28-lane CPU
Important
If you install a large and heavy graphics card, you need to use a tool such as
y
MSI Gaming Series Graphics Card Bolster to support its weight and to prevent
deformation of the slot.
For a single PCIe x16 expansion card installation with optimum performance, using
y
the PCI_E1 slot is recommended.
20
Overview of Components
PCI_E1
PCI_E4
PCI_E1
PCI_E4
PCI_E6