The CPU clock speed status window
Clicking SELECT on the iconbar icon (or using the iconbar menu) will open the Status window. This may take two forms. The default small window shows the cpu clock speed and the cpu die temperature, as shown below.

However, it is possible that the board is fitted with the CJE RTC module with temperature sensor. This sensor measures the temperature close to the board, which will be a function of the ambient case temperature. Assuming CPUClock has detected the presence of the board, an additional field showing the ambient case temperature will be present, as shown below. CJE products such as the PandaRO, RapidO Ig, and Raspberry Pi models may be so fitted. The boards can also be user fitted to the appropriate hardware.

The display will show the current cpu clock speed (switching between the 'fast' and 'slow' speeds depending upon how hard the CPU is working), the cpu die temperature, and the ambient case temperature if the board is fitted with a sensor. The small coloured icon to the right of the cpu temperature changes from green to orange to red as the cpu temperature approaches and then exceeds the set temperature limit (see Choices).
Raspberry Pi fitted with a GPIO driven fan
If a Raspberry Pi is fitted with a fan, and fan control has been enabled in CPUClock, then the status window will contain an indication of the fan state, i.e. on or off. This takes the form of a small icon to the right of the small colour icon. The two states (fan on and fan off) are shown in the images below.

Note that the CPUClock front end updates the values, by default, every 1 second using wimp NULL poll-idle events. See Choices (above). If the wimp is not multitasking at that instant, e.g. processing an image, then the display cannot be updated. However, in general use you should see the speed being switched between 'fast' and 'slow' as you do things in the desktop. Note that the module will continue to read the temperature and do any auto-controlling required in the background, even if the front end is not being updated.
Clicking on the 'maximise' icon at the top right of the status window title bar will extend it. It will now show some additional status information and two additional fields, showing the configured settings for the 'fast' and 'slow' speeds.

The additional status information summarises the temperature variation of the cpu over the past minute of operation. This comprises the average temperature, the maximum temperature reached, and the minimum temperature reached. There is also an indication of the fraction of time spent in a throttled state (expressed as a percentage). This is updated each minute. Remember that the status window is only updated if the wimp is issuing poll events. The statistics are done by the module, so will still be produced if the wimp stops multitasking for a period.
At the bottom of the window are two fields showing the configured 'Fast' and 'Slow' speeds. (Note the figure shown below is of a simpler status window used in an earlier vesion). Clicking on the popup menu button to the right of the 'Fast' or 'Slow' field will raise a menu listing the allowable CPU clock speeds. Selecting one of these speeds will reset the 'Fast' or 'Slow' setting as appropriate to this new value. This is a 'permanent' setting in the sense that it will remain in force until either specifically changed again, or the machine is rebooted.

Reducing the 'Fast' speed may be beneficial in high ambient temperature conditions. It is unlikely there will be any benefit in raising the 'Slow' speed, since this is used when the processor is idling.
CPU speed only mode
If CPUClock is running in cpu speed only mode, then a much simpler status window is used. This contains a field to display the current cpu speed, and the two popup menu buttons and associated display fields to set the fast (and slow) cpu speeds. The window is shown below.
