Yes, if it is PCIe 2.0 x16 (equal to 3.0 x8) it will run identical to Gen 3. All cards except the new Titan X(P) don't use more than PCIe x8 (gen 3) at full load.
Yes, if it is PCIe 2.0 x16 (equal to 3.0 x8) it will run identical to Gen 3. All cards except the new Titan X(P) don't use more than PCIe x8 (gen 3) at full load.