Q:

How can I improve CPU usage in Skyrim?

My system specs are as follows:
CPU: AMD Phenom X4 - 2.4GHz
GPU: Nvidia GeForce GTX 550 Ti (ASUS, Fermi)
RAM: 8GB DDR2
OS: Windows 7 Ultimate, 64-bit
The issue I'm experiencing is that whenever I play Skyrim, after only a few minutes, regardless of my in-game location, my CPU usage skyrockets all the way to 100% and stays there. The fan, of course, also runs at 100% when this happens. When I press Escape and leave the menu open for about 5 seconds, the CPU calms down. It seems the graphic settings are not my issue, as I've lowered my resolution as well as setting the game's settings to 'Low', with no change. I've also uninstalled all of my mods, and unchecked the Dawnguard DLC in the Data Files menu. No change. I also tried uninstalling patches all the way back to 1.1, and still nothing.
What can I do to fix this issue? It's keeping me from playing the game, as I'm 1) annoyed at the noise of the CPU fan when this occurs, 2) concerned about overheating my CPU and causing it damage.

A:

As Serge Bekenkamp already mentioned, the shadows in Skyrim are processed by the CPU, and not the GPU. This is a game engine limitation. Lowering Skyrim's shadow settings will help lessen CPU load.
Other tips that could help CPU performance:
Try cleaning dust out of your PC. See these Super User posts about that:

Is it safe to get dust out of a PC with an air blower?
Suck or blow? What's better for dust?

Also, try the HiAlgoBoost mod. It claims to improve FPS by lowering system resource usage when the player character is in motion. It should help lighten the load for your CPU when playing Skyrim.

HiAlgoBoost dynamically modifies internal rendering resolution in order to increase frame rate, and utilizes various additional approaches to make the game more responsive and smoothly controllable. It does not affect game contents.
HiAlgoBoost features:

Significantly improves responsiveness and gameplay experience.
Significantly reduces in-game loading times.
Increases framerate during character motion by momentarily reducing the resolution.

