FPS Drop for a couple of seconds

Greetings everybody, I have searched through the community and I did not found a solution for my problem. Yesterday, I wanted to play a League of Legends game on my brother's PC. And I got a huge FPS Drop (from 120-180 to 40-50) for 1, 2, max 3 seconds in fighting or something where the GPU has more to render. I tried disabling ULPS with MSI Afterburner, tried Clockblocker, tried cleaning GPU drivers and nothing happens. I play LoL with medium graphics with no shadows on 1080p(720p the same). My specs are:

  • AMD Graphics Card
    • AMD Radeon R7 360 2GB
  • Desktop or Laptop System
    • Desktop
  • Operating System
    • Windows 10 64bit
  • Driver version installed
    • E.g. Radeon Software 17.4.4
  • Motherboard
    • ASRock motherboard fm2a88m-hd+
  • CPU/AP
    • AMD Athlon X4 860K 3.7-4.0Ghz

    • 8GB