Q: Will it only help if I turn it up, or can something "bad" happen?
A: If it's LCD...60 is the standard...you wouldn't notice the difference at all between 60 and 75Hz. However, refresh rate is more applicable to CRT(old monitor). You will see the difference, only if your eyes is sensitive to the flickering(refresh rate) of the screen...Some see it, others don't. If you turn it up...the monitor might not be able to handle it and the screen will be blackout....CRT you will damage it...LCD just inform that is out of range...you just boot into Safemode and reset to the old settings. That's it.