Do you have a power meter connected to see how much power you're draining while mining?
I think you may be correct about the power supply issue.

I believe that on Boost, cards will drain 250W per card
Silent when I tried, GPU-Z gave 150-160W to the GPU, but that would be higher to the wall outlet.
Just there, that would be 1200W approx.
That leaves 300W for risers, SSD, motherboard, fans, etc.  (Anything electrical should only run 75-80% max power)

I just googled "180w Pico PSU" as I have never heard of that.  What exactly is this connected to on the rig?

Things I would try:
1. Run all of the cards on Silent instead of (3) on Boost and (3) on Silent?  That would lower the watts.
2. Ensure that your Windows 10 Power Management is set to "High Performance" and ensure the Hard Drives Never shutdown, screen never shuts down, PCIe slots can't be managed, etc (the regular stuff)
3. Review PCIE/SSD/HDD in "Device Manager" and ensure that the Power Management is disabled on all of these drivers