Question Games lagging on good pc

[Roei Paul]

Games lagging on good pc
my specs are
gtx 960 2gb vram(gigabyte)
intel core i5 4460 3.20gz
8 gb of ram
and when i play fortnite only low settings are play-able
same thing with overwatch
and these are games which i used to run no problem high settings... is formatting my pc a viable fix? or is there any way that i can try improve it?
Thanks

 

[rgd1101]

What the cpu/gpu temp and usage during the game?
make and model of the psu?

 

[Roei Paul]

temps are ok..
psu- idk but its enough for the pc..