Does anyone know why this is happening
É chamado de SpeedStep
how to fix it?
Não há nada para "consertar" per se, quando a carga aumenta, a frequência aumenta.
Além disso,
Under Microsoft Windows XP, SpeedStep support is built into the power management console under the control panel. In Windows XP a user can regulate the processor's speed indirectly by changing power schemes. The "Home/Office Desk" disables SpeedStep, the "Portable/Laptop" power scheme enables SpeedStep, and the "Max Battery" uses SpeedStep to slow the processor to minimal power levels as the battery weakens. The SpeedStep settings for power schemes, either built-in or custom, cannot be modified from the control panel's GUI, but can be modified using the POWERCFG.EXE command-line utility.