Max Foreground FPS and Maz background FPS what to set?

Hello. I want to play on the smoothest settings and I set everything to low. But what should I set for my Max Foreground FPS and Max background FPS? http://i.imgur.com/KGUWeeD.jpg
May someone tell me what I should put? Thank you

[lax]

ISBoxer has FPS limiting built in and configured via the CPU Strategy Wizard. You can disable the game's FPS limiting functionality by unchecking the boxes, and ISBoxer will take over.