4 pci-express lanes are requires to support 10 gbps.
Explanation:
PCI is the one that determines the devices that are connected to the motherboard. In a single PCI slot, there are lanes such as 1, 4, 8, 16. Two unidirectional differential pairs are present in each lane. PCI 4.0/x4 can able to handle 7.88 gbps.
10 gbps = 10000/8 = 1250 mbps. The 4 lanes can be enough to support the card with 10 GB per second.