I cant use 5x4090 turns off if run hashcat with the parameter -O

[slyexe]

Yea whats the rated outlet your connecting your power supplies too? If its a standard 15 amp 120VAC circuit you would be limited to ~1800W But judging by your calculations I'd say you're already using 220VAC or on a bigger circuit. The click in the power supply does that occur when you do a normal power up? Or strictly when the PC crashes running hashcat? Does running an attack work in hashcat or does it also crash? try lowering your workload to 2 and see if you have the same results. Enabling Optimizers in benchmark should not change anything other than seeing different results. Power consumption should be the same whether Optimizers are enabled or not.

What version of hashcat are you using?
What Graphic Drivers do you have installed?
Are you able to do hashcat -I and paste it here to confirm all information.