Fps Issues

[Thanodes]

So recently I have been having issues on league of legends where if I have it displayed on my primary display once I tab in and out I drop fps from 200+ to 80 and if I do borderless it stays at 80fps but if its windowed the fps is remains at 200+. Now if I set the display that league of legends in displayed on as my secondary display all the fps issues are fixed  but once I change it back as my primary display the issues return. I have no real clue on how to fix this. I have already done a clean install of drivers for gpu, uninstalled the game and deleted the files and then reinstall, rolled back windows and gpu to older updates where it worked fine but no dice I don't know what else to do

[bmx6454]

been a while since i played Lol, but iirc there is an option to repair the client. i would try that first. what are the pc specs? and what refresh rate is the monitor?

[Thanodes]

I have already tried the repair option, as a last resort i've even reinstalled windows no dice lol

both monitors i'm using are both 60hz and and v-sync is never an issue and is also never on  just a weird issue on this one game if its played on my primary display every other game works fine 

the pc specs are

CPU:ryzen 5 1600

GPU:gtx 1070

MB: B450 Pro Carbon

16 GB Corsair vengeance  3200mhz

750 watt psu