It can reach up to 100% if you use many programs at once. A computer is a multitasking computing device. But still it has limitations. If you use low RAM occupying programs, it's much better than opening several programs at once.
Try unloading some applications or if your computer is already really old maybe its time for an upgrade
A CPU will run at 100% when you have a lot of "stuff" going on. That stuff can be things you WANT to run, or it can be spyware, viruses or even benign applications that you thought might be nice to have but often just take up space and processor cycles.
You just click on it and say end now or just delete
Under the "PROCESSES" tab in the Task Manager, sort by the "CPU" column, and identify the process that's hogging the CPU. Then, based on what it is, decide whether to end the process, and possibly whether to wipe it off the computer entirely.
You want you computer to use 100% of your CPU. The more CPU your computer uses, the faster it is working.
Press CTRL-ALT-DELETE and click on Task Manager. Go to the Processes tab and look for which process is taking up 100% CPU. Then search on Google for "processname.exe 100% cpu"
With modern processors all that should happen is that they will automatically slow themselves down (though the usage will still show as 100%) to prevent the danger of overheating. In theory, at least, running at 100% usage should not be harmful to the processor.
It could be that you are running something that causes the CPU to be running at 100% all the time, or you have concurrent apps/processes that are keeping the CPU awake (same effect as the CPU running 100% all the time).
It depends on the specific CPU, but on average, a typical CPU weighs around 50-100 grams, which is equivalent to 0.05-0.1 kilograms.
You can gain anywhere from 5-100% depending on how old your previous cpu was.
it is most likley a virus right click on taskbar and enter task manager and see what the cause is.
Usually the fan will turn on when a certain heat is reached.