Never used a GB mobo but you can try to change the load line calibration switching between presets.
Also i had the opposite bad experience with with B760 and 13600kf. Abnormal power draw and voltage spikes. Voltage fine tuning didn’t solved the problem.
Only solution was to switch to z690/z790.
Try to monitor the p-core frequencies, if they goes under 5.1GHz during test the cpu is not getting enough Watts or Volts.
Is the system throttling somewhere? (I know 14th should behave better than 13th but silicon quality may net be the same)
Just get 192+ GB DDR5 Ram. 1 GB per tab should be fine.