Slowdown issues - is it OS or hardware related?

Since a while i experience some slowdown issues on my notebook. For example i run a CPU intensive game, like GTA IV. I experience a lot of sttutering in game, and after i close it the notebook freezes for a few seconds, and if i continously try to close some already opened aplications like firefox or messenger, i get a task manager error saying explorer.exe is not responding. If i choose to end the process, the desktop turns light blue, and i can't do anything until I restart the notebook. If i take a look in the task manager at processes tab, the system idle process eats a lot of CPU. Even now when im writing this with only firefox opened, my system idle procces says its eating 80-97 CPU, mostly over 90, is this normal?
I experience a lot of slowdowns in games like Dragon age or The Saboteur, which didn't happen before. Could it be that i undervolted my CPU?
Before i undervolted it, the notebook was making a lot of noise under heavy load and was reaching 80 degress. After i UVed it i now get max 68 degress C and the CPU doesn't make such noise. During this heavy load i can easily alt+tab in dragon age, but if stay to much and then switch back to the game, it takes a lot of time to load it, and it loads it exactly when the CPU is starting to make noise again. I don't remember doing such things before.
Is this OS or hardware related?

 

when you say your screen turns light blue, has it got lots of writing on it?
if so thats the dreaded blue screen of death. but dont panic is not as bad as it sounds.
download Who Crashed which will give us a better idea of the problem.

 

no its not bsod, i know what that means and its not
Here's a list of my proceses, the cpu usage seems stable at idle but sometimes it randomly jumps to 90-100% for 1 second and then its back to normal




and





also, the number of proceses is not always the same, sometimes its diference of 1 or 2, even if i dont open/close any aplication

 

Yes. That's just Windows' way of telling you that the CPU is mostly not being used at the moment.

Yes. Here is the first diagnostic step in case of such issues: return all voltages and clocks back to stock values. If the problem goes away, then it's caused by something you did. If not, then either the hardware is fundamentally faulty (run memtest, GPU and CPU stress tests, etc.) or something is wrong with the OS.

 

too much undervolting might be an issue.. i would reduce voltages by little only from stock...

 

Do you remember what I said in GTA IV therad about a week ago?

Anyways, now I'm here to help
First do as Althernai said, turn your voltages to stock. If you still have the problem, you can try a app named GameBooster. This will shutdown backgronds processes and give you a few more FPS. And I see processes which is useless, like Google Crash... (Google installer). Or you can try the app first, if you still have the problem it is because of your background processes.

Tell me how it turns up