There is a role to enable higher resolution on dashboards but only applies to the 30 days or less time range.
This will allow you to do 5 minute for 30 days, for example. But above 30 days, only the system defaults are available.
Below are the default resolution values available
CA Performance Center determines the default (recommended) Resolution value for each view based on the calculated Time Range in seconds:
Time Range >= Seconds per week: Resolution = 1-Day
Time Range >= Seconds per day: Resolution = 1-Hour
Time Range >= Seconds per hour: Resolution = 5-Minute
For added flexibility, CA Performance Center lets you override the default Resolution value for views using one of the following selections:
When determining the Resolution values that can be selected in the View Settings dialogs, CA Performance Center takes into account the currently configured Time Range for the view. As a result, only the options that match the following condition are presented:
Time Range (in seconds) / Resolution (in seconds) must be greater than 4 and less than 800.
Therefore once you go beyond this threshold of 33 days, only daily thresholds are available as this is when the 800 sample limit would be reached.