Here is a short 101 on this subject. Later, we will post a lengthier FAQ item. The CPU in computers is actually 100% utilized no matter what is going on, except when it is powered off, or stopped. There is a secret "idle" task running in the background that runs at lower priority than everything else in the computer, even lower than the grid agent. The idle task counts up the percentage of the time it runs and calls this "idle time" and reduces the reported CPU utilization figure accordingly. Neither the grid agent nor the idle task will run if your computer has other work to do. However, since the grid agent runs at slightly higher priority than the idle task, the idle task won't run at all and thus report that your computer is always 100% utilized. These two tasks account for the otherwise remaining unused cycles of your CPU.

Most modern computers have the ability to change clock speeds instantaneously. When the system sees that the idle time task is getting serviced a lot, it lowers the clock speed of the CPU to consume less electrical power and consequently generate less heat. If it sees that the idle task is not getting a lot of the of the CPU time, it raises the CPU clock speed so that the tasks doing useful work run faster. The activity that creates most of the heat inside the CPU chip is the many transitions of logic gates between "0" and "1" values. There are many millions of logic gates on modern CPU chips and when you have one running at a 1.5 Ghz clock speed, there are 1.5 billion opportunities per second for the millions of logic gates to have transitions. Even though each transition for one gate represents a tiny amount of heat, when you have millions of such gates doing this billions of times a second, you could have quadrillions of transitions occurring per second. So, if the CPU clock speed can be temporarily cut in half, this cuts the heat production about in half as well. So, when you run the grid agent, the computer will run at a higher clock speed more of the time and get hotter because the idle task does not run. The same thing happens when you play intense video games or perform other intensive tasks on the computer.

Most computer manufacturers design their computers to handle running at full speed continuously, by using sufficient heat sinks and fans in the computer. Laptops often provide user controls to manually lower the maximum allowed CPU clock speed to save battery power with the side benefit of running cooler. Many computers also have additional measures to automatically shut off the machine, for example when it gets too hot from dust filled air pathways, if a critical fan stops running, or if the room temperature is too high to permit adequate cooling. Unless you have a machine, which is defective in some way, or has inadequate cooling, it should run fine. However, running at higher temperatures can reveal latent problems with marginal components in your system. This is often the experience of zealous enthusiasts called "overclockers" who modify their machines to run at higher clock speeds than for which they were designed. If you are concerned about your own computer, then you may want to contact your computer's manufacturer(s) for advice, and take necessary steps to provide sufficient cooling and setting of proper CPU clock speeds.

- World Community Grid admin team