i've not modded anything yet as im just starting out
I'm set up with simpleminer OS at the moment but i know bios modding is harder with it
was considering installing windows onto a ssd drive to make it easier??
even then would it not be an good idea to get a 3rd server psu to bring the load down on each of the other 2?
thanks
Yes, I would rebuild your PC with Windows 10 if you are more familiar with it, but it can also be done with Linux if you have the patience.
The BIOS mods along with under-volting down to the low 900's (925mv, 950mv, etc.) would bring your wattage down by quite a chunk and you should easily be able to run your rig with the PSUs you already have.
As I posted earlier, you can easily shave about 40 watts off of each cards draw thus reducing your entire systems draw by about 500 watts. This in itself should eliminate your need for an extra PSU and should also run your current ones much cooler, thus quieter. I run RX580's at around 130 watts each (which would be almost 50 watts per card less than you are using) with 925mv and 1040/2100 clocks yielding around 29.5 Mhash/sec for each card, which is pretty typical. Good performance versus watt ratio.