Performance issue with Asus ROG strix x570-F Gaming with 5950X

[CuRSeDGaMInG]

Hello there!
Okey,
So my fairly new ryzen system act very strange and I need some serious expert advise and I will try to give you as much information as I can.

I will start with the problem and then what I've done so far to try to figure out whats wrong.

First my specs:
Asus rog strix x570-F Gaming
Ryzen 9 5950X
Asus Ryujin 360 AIO
Corsair vengence 4x8Gb ddr4 cl18 3600mhz (CMK32GX4M4B3600C18)
Bootdrive: 1 x intel m.2 512Gb SSD
Windows 10 Pro "20H0"
Gamedrive: 1 x intel m.2 2Tb SSD
Storage: 2x seagate barracuda 7200rpm 2Tb RAID0.
GPU: Asus Rog strix RTX3090 OC
PSU: Evga G2 supernova 1300W
Display: Samsung Odyssey G9 240hz

So I was really unhappy with the performance of my Asus ROG Strix RTX3090 OC, it didn't show those numbers that I seen people got in various benchmarks.
I tried to run a 3dmark timespy benchmark and saw that the gpu usage was 30%! And powerdraw around 50%. No gsync, or framecapping.
Got score of 5000 ,.same spec pc's were getting 20.000+ ,.
And same in games, the gpu usage was fluctuating like crazy even at very low fps.
It's like a severe cpu bottleneck, something is holding the gpu back,.
And what i can tell from the cpu score is that it is all over the place,. Timespy 10.000 - 14.000 if I just run it a couple of times.

What I've tested so far is to try the rtx3090 in my secondary system a i9 9900K no issues.
Tried the 1080Ti from that system in my ryzen system and it behaved the same as the rtx3090, low usage.
Tried a different PSU a corsair AX860i, same issue. At this time all storage drives were left without power so only the m.2 drives were still in the mix.
I put the 3090 back in and reinstalled the evga psu and then I reinstalled windows, first run I did in 3Dmark now looked promising and gave me a score of 18.000. The GPU was still not locked at 100% usage but between 96-99%.
But then it came back , tried doom eternal at 5120x1440p 240hz and the GPU sat at 56% usage and FPS 100-130.
And timespy was back to perform like a gtx560.
I run the cpu at Auto, only use "xmp" for the memory but have tried to have that on auto aswell but without any success.
Someone asked me if I connected my monitor to the gpu or the motherboards built-in apu and it is connected to the gpu ofc, displayport 1.4.
Temps are all good for both cpu,gpu and mobo.

Any ideas were to look next? Bad memory? Bad cpu? Bad mobo? Bad m.2 drives? Conflicts?

I really need your help! Before I go back to intel again, 😅 haven't had a amd chip since the athlon thunderbird 1400+ ,..