GPU underproforming

[finlish]

please help! i have a 1080 ti and for some reason every few days it will be working fine and then my fps will decree randomly and when i reboot my PC it goes back to normal. the temps are fine around 72 degrees and i have changed all o the settings in control panel to try and fix it but it still inst working. i have no viruses on my PC as i have downloaded multiple anti virus software and my PC is free from viruses. someone please help as there is no help anywhere i search this up! in heaven benchmark at ultra settings at 1440p i see around 70 fps and no wit is at 14 fps i cant fined out why. it is not my drivers as i have uninstalled them and reinstalled them. 

[eeeee1]

could you reply with:

other specs

games

doing anything else in the background?

[finlish]

i have a ryzen 7 3700x overclocked to 4.3ghz

32gb of ram 3200 speed 

1tb nvme m.2ssd 

evga 650 watt 80 plus gold

i have only a few things running in the background like discord and steam

[finlish]

i deleted them as soon as they was done virus scanning. i used multiple anti virus because some anti virus software  would pick up different things because they use different algorithms if that makes scene,