How to get access to advanced PCI-E bios settings£

Hi all,

I have been on a long quest to reduce the power consumption of my systems, and have dove into multiple rabbit holes.

Long story short, my issue seems to be with ASPM and PCI-E lanes.

I have an ASRock B760 Pro RS/D4 where I have connected a NVME drive (chipset) and a LSI HBA on the PCI-E x16 (top one, CPU).

This has had the effect of the system not being able to enter higher C-states, namely anything above C2/C3. I thought this could be an issue with ASPM, but every device supports and has ASPM enabled. The settings are also enabled in the bios.

After some googling I found this thread: https://community.intel.com/t5/Embedded-Connectivity/Using-x16-pcie-slot-disables-low-package-c-states-ASPM-Alderlake/td-p/1555031

This seems to be the exact same issue I have, where the solution is:
> In your BIOS:
>
> Advanced -> Admin -> Chipset->System Agent(SA) configuration->PCI Express Configuration
>
> Set Multi-VC to Disabled on both of PCIE Root Port 1 & PCIE Root Port 2."
>
>
> Setting Multi-VC to Disabled could help reaching C10, meanwhile, by being enabled, the system can only reach C3.

However, this option is not exposed in the BIOS.

Is there any way to expose this option so that my system can finally be more efficient and conserve some of that (expensive) energy :)?

Thanks in advance!

It?™s frustrating when BIOS options aren?™t accessible. You might try updating to the latest BIOS version, as it sometimes unlocks hidden settings. Alternatively, using a tool like AMIBCP could expose advanced options https://sassastatuscheckbankingdetails.co.za/, but proceed with caution to avoid bricking your system. Have you also checked if ASRock support can provide a custom BIOS or guidance.