It’s hard to diagnose without actually seeing it. But I have a couple thoughts.
What you are describing is indicative of something sporadically taking a LOT of your memory and CPU, basically making your machine SO BUSY for a few moments that:
a) the processor is drawing more power, meaning
b) that the processor is hotter, meaning
c) that the fan comes on
In addition, if some process is really going crazy and gobbling up all the processor capacity and memory, it would have the effect of making other processes (mouse, keyboard, etc.) wait until that crazy process is done.
What you are describing fits perfectly the idea of a rogue process.
Two things to do:
1) go to a command prompt and type TASKMGR (Task Manager).
on that display, go to the Processes tab
you have a choice between Fewer Details and More Details. Choose More Details
You will see a display with the program name (on left) and a bunch of columns on the right.
The ones you want to look at are CPU, MEMORY, and DISK. Let the PC sit for a few minutes. Your CPU should be somewhere around 10–15%, your Memory 20–30%, and Disk 15–20% if you’re letting it sit.
If your percentages are higher, then something is going on. Click on the percentage for CPU, so that it sorts by percentage, highest to lowest. That will tell you what process is eating your CPU. Same with Memory (which is probably where your problem is), and then also with Disk.
Now – if you see things spiking and the percentages going up and down that is an indication of what program is causing your problems.
If it stays calm, then keep TASKMGR open, but do something else – open a browser, listen to music, anything. And see how the numbers and percentages react.
My guess is that there is a misbehaving process.
So what do you do about it? It depends on the process. At a minimum, while still in TASKMGR, go to the Startup tab. That will list all the processes that start up when you reboot your computer. You will have a bunch where the status is ENABLED.
Look at them – my suspicion is that when you bought your computer, a whole ton of programs start at boot – which are totally unnecessary and gobble up your CPU and memory.
Right click on the line with the program name, and select DISABLE for the programs that you don’t know or recognize. Don’t disable WIndows Host Process or your mouse or anything important.
Exit and reboot, and see if things improve.
There are other things to try but they get more complicated.