Quick Feedback:
The X710 supports ASPM.
i changed my Mellanox ConnectX-3 card with the Intel X710-DA2 in my Sophos XG-Firewall.
Here are the outputs of LSPCI:
Mellanox Connect-X 3 (CX312A)
LnkCap: Port #8, Speed unknown, Width x8, ASPM L0s, Latency L0 unlimited, L1 unlimited
ClockPM-...