How to reduce CPU usage by controlling the Affinity

Since yesterday I was trying to use HandBrake to convert my videos from MTS to MP4 format but for some reason my computer was shutting down all of a sudden. Today morning I found that Handbrake was using 97% of the CPU and my laptop has developed heating issue. Both of them combined was shutting down the complete system.

Now if your computer or laptop has multi-core cpu it is possible to control for any process on how many CPU core they can use using Affinity. Here is how :

  • First keep your program running which is consuming the CPU and make sure you have administrator privilege for this.
  • Launch the Task Manager and find the program. The best is to sort by name or by CPU consumption.
  • Right click and select Set Affinity.
  • This will pop up a small window where you can see how many cpu core the program is using. By default all of them will be selected which you can change.
  • Deselect one if you have two or two if you have for. Adjust is so the CPU usage drops by that amount. If you select only one cpu of four the cpu usage for that process will be 25% of what it using.

Done this your CPU usage will definitely come down. There is another trick that you can try. Right click on any process and Select Set Process Priority. Here you can reduce how the OS gives importance to a program. So when you have multiple programs running you can give one program more importance than others using this but if you have just one program which is running, affinity option is better.


  1. Thanks it works, I have a Alienware laptop, it has 7 cores and for some reason Handbrake was using 100% of my CPU. When I tried your trick all 7 cores were ticked and only have one ticked and now it’s only using 21% Thanks so much.

  2. But that will overload that one isolated core. It’ll create one even bigger problem. Instead of the entire CPU overheating, you’ll get only one core overheating and doing the job that the entire CPU should do.

  3. @david I was worried about that too so I figured it wouldn’t hurt to set it for a moment and if it started to overheat, to change it back.

    Fortunately the temp of both cores dropped to below 60C at this point whereas it was hitting near 80C with affinity set to both the cores. The trick is to set it to the single base core (core 0) instead of core 1 and above. Which will overheat it.


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