>>101216999
I do it via commands like
sudo nvidia-smi --lock-gpu-clocks 0,2000 --mode 1
IIRC you can then reliably draw something like 300 W per 4090 without running into stability issues and with ~90% of the maximum potential performance,
Notably setting a power limit via nvidia-smi does NOT help to reduce spikes in power consumption.
If you don't limit the boost clocks 4 4090s running in parallel can already lead to instability.