Yes it's 100% compatible and here is some great info on 2.0 vs. 3.0 , virtually no loss in performance.
https://www.pugetsystems.com/labs/articles/Impact-of-PCI-E-Speed-on-Gaming-Performance-518/
Impact of PCI-E Speed on Gaming Performance
The GIGABYTE GA-78LMT-S2 has the required 1 x PCI Express x16 slot. It is a 2.0 and not 3.0, but all modern GPU's are backwards compatible and you won't suffer any performance loss from the PCIe v.2 slot.
Yes it's 100% compatible and here is some great info on 2.0 vs. 3.0 , virtually no loss in performance.
https://www.pugetsystems.com/labs/articles/Impact-of-PCI-E-Speed-on-Gaming-Performance-518/
Impact of PCI-E Speed on Gaming Performance