LOW FPS DONT KNOW Y NEED HELP!!!

so i have a 1050 ti 8th gen I3 CPU 8 gigs of ram and a 1000 gigabyte hard drive and iv been updating my drivers every time a new obe comes out. my fps will start at around 200 in game but as soon as laning phase starts it drops to around 120 and when i get in a team fight it will be insanly unstable droping below 60 iv also lowered all my in game settings as well. i dont undersatand mainly bc i thought lol would be fine on these speks what should i do