That`s not "100 MB", that`s "100%" - scaled value (between minimum and maximum samples). You can delete first performance counter, and then invoke properties dialog for needed counter. There you switch to "Graph" tab, select View - "Line" and set Vertical scale - Maximum to overall amount of your RAM in megabytes (I guess). I will try this too now... PS You can see actual numbers in fields under the graph - "Last", "Average", "Minimum". PPS I never view performance counters in Line view. I use Report view.