During my research I found that the blue line was the "maximum frequency" and that it's not a great indicator of CPU overload but should still be correlated to the current CPU load. In my case, no process stands out as being overly busy (double checked with Process Explorer).
The fan on my laptop is not blowing that hard, like when I'm building a big .Net solution, but it's not silent either. Just that constant low-grade blowing...
Any idea where I should look next?
CPU frequency isn't a measure of workload at all. Windows may adjust it based on workload, but it isn't actually a sign of work being done. It indicates a capacity to work at a given speed; it isn't saying that it is utilizing that capacity.
Modern CPUs (paired with modern OS's) adjust their frequency when advantageous to save power or reduce heat generation (called Throttling), and will ramp up to MAX or Turbo frequencies when its determined that its useful.
Keep in mind this does not indicate usage however. if a CPU is on max frequency, and performing a task on 1/100th of its cycles, its using 1% CPU. If the frequency is reduced, its likely that that same set of tasks would still only use 1% of cycles, but the time that a cycle takes is slightly longer. It affects how fast an instruction is processed. Generally speaking one instruction is run per cycle.
Check your power settings, and your BIOS (bios can affect APCI). It is likely that your system is set to never throttle the CPU. Or perhaps you are observing the low frequency reading, and your PC hasn't had reason to scale up to max frequency while you are looking at it.
See more about processor frequency scaling here: How does windows "limit" the CPU (Power Options / Battery saving)
Personally, I think its inclusion on that graph is just convenient for MS, but not the best way to present that data, precisely because it is not about consumption, its about what is there and available to be consumed.
