Rename the existing nvml.dll in System32 to something else (e.g. nvml_old.dll) then copy the one from the archive in System32. After that restart Windows, and you should be able to delete the nvml_old.dll from System32.
Please add support for DAG epoch above 500 because I'll be calm and other mining programs have already done so.
+1
Phoenix may stop mining after a certain amount of time, as it did with Claymore Miner.
Better to add large DAG support in advance.