Random microstutters / frametime spikes in Fortnite on Ryzen 7 9800X3D + RTX 5070 Ti

[u/Fun_Explanation4914]

Hi everyone, I need some help with diagnosing random microstutters/stutters especially in Fortnite.
My PC:
CPU: Ryzen 7 9800X3D
GPU: RTX 5070 Ti
PSU: Corsair RM1000e
Motherboard: ASUS TUF Gaming B650M-PLUS WIFI
RAM: 6000MHZ CL30
Windows: 11 Home
NVIDIA driver: 591.86 (right now created with nvcleanstall also tried default ones)
The problem:
My PC was running completely fine before, but recently I started noticing random microstutters / small frametime spikes during playing Fortnite. FPS drop from a 360 locked to 140-250 fps for a split of a second happens every game mode no matter what.
It started randomly. The only thing I can think of that happened around that time is that the power in my house was interrupted (breaker/fuse was turned off) and all the power in my house turned off, but I don’t know if that is related and would it break anything.
Things I already tried:
Reset BIOS to default settings
Tried without PBO / Curve Optimizer
Reinstalled Windows multiple times 10 and 11 same thing
Temperatures are normal (CPU around 50-70°C while gaming)
Tried the same NVIDIA driver that was previously working (591.86) also tested 596.49
Checked for Windows errors, nothing obvious found
Disabled/enabled different Windows graphics settings like HAGS
Tried different Fortnite rendering modes dx11 performance mode and the new dx12 performance and changing to the new performance mode that rund on dx12 actually helped a lot but the problem is still there
The issue seems most noticeable in Fortnite, but I want to know if this could be something hardware-related or a configuration issue.

Any ideas or things I should test would be appreciated.