pc freezes for few seconds

hi all, in the last months i've been facing this problem, as in title:
quite often, most of all if the computer is doing some "heavy" work like watching a video or video games, it freezes, leaving me watching the same still screen for a few seconds and not being able to move the cursor or pressing any letter. then screen gets back "moving". audio often continues even when the screen is still.
i've already installed the last video drivers, and the pc is surely "clean" by virus or malwares because i've installed windows 7 a few days ago, and formatted all the hdd.
also, i had windows 8 before, and the problem was there already. i'm quite afraid it's an hardware problem, but at least i'd like to do some other tests before being sure about it.
last thing, pc overheats, reaching 80° if i do something "heavy" for a lot of time, but the problem doesn't occurr after the pc is heated, even when it's still cold.

sorry for my english, hope what i wrote is clear.

scarecrowGin said:

hi all, in the last months i've been facing this problem, as in title:
quite often, most of all if the computer is doing some "heavy" work like watching a video or video games, it freezes, leaving me watching the same still screen for a few seconds and not being able to move the cursor or pressing any letter. then screen gets back "moving". audio often continues even when the screen is still.
i've already installed the last video drivers, and the pc is surely "clean" by virus or malwares because i've installed windows 7 a few days ago, and formatted all the hdd.
also, i had windows 8 before, and the problem was there already. i'm quite afraid it's an hardware problem, but at least i'd like to do some other tests before being sure about it.
last thing, pc overheats, reaching 80° if i do something "heavy" for a lot of time, but the problem doesn't occurr after the pc is heated, even when it's still cold.

sorry for my english, hope what i wrote is clear.

Have you physically cleaned the system, taken the sides off and actually removed any dust buildup and the like with special emphasis on the fans? If that has been done or if you try it without success, you may have a problem with the heat sink on the CPU.

Sir George said:

Have you physically cleaned the system, taken the sides off and actually removed any dust buildup and the like with special emphasis on the fans? If that has been done or if you try it without success, you may have a problem with the heat sink on the CPU.

i didn't yet, i've just bought the termal paste and when i'll receive it i'll do it, but i'm not sure that might change something, as, as i told, freezes happen even when the pc is still cold. i'll try and tell in case.
any other tips? :)

i completely cleaned it and put paste on the cpu, the temp is lower, around 65° but the problem is still there. i just discovered that my cpu was overclocking by herself (never used something to overclock it) from 2.3MHz to 3.1... i'm afraid somehow the cpu broke, but how can i be sure about it?