Just Core i3 and up. Dolphin emulator supports AVX I believe, and I know of one game (Grid2) that is compiled to use AVX instructions, which suggests games CAN be made to take advantage of them but typically aren't/don't. Part of the reason AVX hasn't caught on is that you need a different executable for CPUs that can't use it, and Intel segments their CPUs by instruction sets so a good percent of CPUs still sold don't support them, meaning games can't be compiled to use them and be universally compatible even with CPUs sold in 2017, despite AVX being 6 years old at this point.