Why PUBG stutters a lot in my PC?

My pc spec is i5 13400, 8x2 16 gb ram, rtx 5070 ti, I have installed the game in sata ssd of western digital. the game is stuttering a lot, even in everything in low setting? I have tried by capping fps limit at 100, but then also it is stuttering, some times fps drops as low as 80-90. why? what is the solution? help please. but when I play with my pc, it give fortnite gives 250-315 fps at performance mode, with no stuttering.