You should check resources - PCIE which ones are directly connected to CPU and which are to chipset. All devices inc USB devices are taking up resources. DO a count and subtract from the total available for your motherboard. Maybe take out a device - a drive, a GPU etc... (experiment) until you see a happy compromise.
For example, The ASROCK TRX40 Creator features 88 PCIE lanes, 72 of which are useable to the end user. The Threadripper AMD CPUs utilise 56/64 PCIe 4.0 lanes.
Chipset vs. processor allocated PCIe lanes
The PCIe lanes on a motherboard originate either from the processor itself or the motherboard chipset.
Generally, the processor lanes are reserved exclusively for the graphics card x16 slots and M.2 slots for high-speed SSDs, as they require to move data without being bottlenecked by the chipset.
On the other hand, chipset lanes connect to onboard USB, other M.2 and PCIe slots, and SATA. The chipset itself transfers data to the processor via a dedicated 4-lane PCIe bus.
So, all devices connected via PCIe lanes to the chipset will have a cap on their maximum bandwidth leading to bottlenecks
Don't forget to run MMIO Opencore checks as u go.