System can't reach deep C-states (>C2)

Hello, I hope you're having a nice day. I installed unraid about a week ago, and I'm really proud of successfully migrated all my server from windows + linux to unraid. (20 TB of data).
Now the server works well, but I want to cut electricity costs. I already did the second server for the same reason, and this one is the 3rd version. Unfortunately, I am unable to enter a deep package C-State. On powertop even after auto-tune, I'm about 95% on C2. I have followed a lot of forums about the bios settings and changed them a lot everywhere, but nothing goes. I'm always stuck with C2, and my current “idle” load is 77W. For comparison, the previous server which was 2 machines idled at 25.
I have an HBA that could block deep C-States but for the moment, even with it unplugged, I can't go past C2. So the card is not the problem for now.
Here are all my specs :

CPU : intel I5 12500
MB : MSI MAG B660M BAZOOKA DDR4
RAM : Kingston Fury Beast 16 GB 3200MHz x3 (their timing is lower I haven't changed the base timing, I think they are 2666 currently)
PSU : Supermicro PWS-920P-SQ
HBA : Fujitsu D3307-A12 IT flashed (unplugged for the package testing)
HDD : I have 6 HDD, but their specifications are not important as they are unplugged when the HBA is unplugged

And nothing more, that's why I'm asking for help on this forum, most of the time guys are stuck in C state because of bad SSD, or NIC etc… But I test the build naked, so I'm pretty lost.

Thanks, have a nice day !