Today my friend Jeff hit me up with an interesting question. His quad-core HP DL585 is supposed to operate at 3.4 GHz, but Performance Monitor was showing it running at 82% of the maximum frequency–2.8 GHz.

My first thought was that the difference was the metric AMD uses to make it easier to compare their processors to Intels higher-frequency chips–and I was really wrong. When I investigated the Performance Monitor counters Jeff was looking at, I discovered a counter I hadn’t used before: Processor Performance\% of Maximum Frequency, as shown above.

This counter shows the current frequency of the processor. Modern processors can slow themselves down a bit to save power when they’re not doing anything high-priority. A few years back, it was just mobile processors that did this. Today, it’s pervasive–mobile computers, desktops, and servers scale back frequency when they’re not busy.

As shown here, you can configure the minimum and maximum processor states from the Power Options dialog box (Control Panel\Hardware And Sound\Power Options\Change Plan Settings):

You might also be able to configure settings from your computer’s BIOS/CMOS.