Computer freezing and audio choking

I had reformatted my computer 1 month before because it was having virus problems. After reformat, it was running very smoothly from last 1 month. Suddenly now, from 2 days, it has started freezing while starting any application. Even if I start any software, start a new browser and sometimes even when I start a new window it hangs for some fraction of seconds and then become normal after some time. When I start a game or play music, it freezes the video for some seconds and chokes the audio as well sometimes giving some looping sound.

I am not able to understand what this problem is! I have scanned my PC with antivirus but there is nothing crap detected. Already, my pc is formatted recently. How can I fix this issue?

You should scan your system with malwarebytes. It might be that there some malware that your antivirus is not tracking maybe because it is not latest updated. Which antivirus you are using?

As you said that your computer was already affected by virus and then you formatted your PC. I doubt that you might have formatted only your C drive and installed OS but there might be some folder or location where the traces of those viruses were still residing and they erupted again after 1 month when you run or visited that location again.

What is your graphics card you are using and what is the PSU wattage? Your PSU might not be supplying sufficient power which is why it is hanging for some time and then becomes normal.

My PSU is 400 watts. Is it of less power? I had never guessed that PSU can also cause freezing problem! Because as the problem describes, the screen hangs and the audio chokes for some time and in that the mouse remains at a certain point and moves and then again hangs. This happens frequently for some time and then comes to normal.

It is actually some program that is eating up your system resources to maximum. You can check this in Task Manager. Check the processes in Task Manager and mark the process that is running between 100% cpu usage and 10% cpu usage. Tell us what that process is.

I doubt strongly that it is surely some malware consuming high CPU usage.