OK, I'll try to explain it so that you can understand it. For games to run smoothly, they must run synced to the monitor refresh. For this you should use vsync or triple buffer, otherwise you'll experience tearing on screen. Now, this is with 60hz games, and supposing the res mode you're using in your PC is 60hz (120 hz will also be ok, but there will be some pixel doubling in moving objects). Any problems so far? OK. Now, what happens if the emulated game runs at 57hz, or at 59,63hz (cps2). There will be a mismatch between the emulated game rate and the actual rate you've set. Result: hiccups in scrolls and moving sprites. The higher the mismatch is, the more frequent the hiccups will be. Solution: set exact refresh rates for every game, which is really a pain considering the variety of res modes and refresh rates there are. Easy solution: tweak these games to be pure 60hz (they will run a percentage faster up to 60). This is what SMOOTHMAME is for. I can't understand that you say that SmoothMAME was useless, because, in my opinion, it has been the best and most useful MAME build I've ever used, and I couldn't be more grateful to Twisty for releasing his modified drivers during all this time. If you are 100% purists and don't want any speed tweak, I understand that you don't use global 60hz, but if you want smoothness and perfect performance, it's the way to go.