What happens when PCIe boost circuits are overloaded? In my understanding, the 2010 Mac Pro is rated for 75W of power for each PCIe slot, plus 75W for each of the two 6-pin boost (aux) circuits.  I know it's possible to exceed these limits, because I do it regularly. At what point does it have some effect, and what is that effect?  I'd like a very specific answer, not just, "it crashes".  My guesses:


A thermal or power sensor trips and kills power to the offending circuit.
A sensor trips and kills power to the whole PSU
The motherboard traces melt and cause a fire
The OS kills the process that is over-using the GPU


Obviously, any of these options would cause the computer to crash.  My computer sometimes reboots spontaneously when I'm doing heavy GPU processing, and I just want to understand exactly what is happening.

Interesting sidenote:  after this type of crash, I always have to reinstall the Blackmagic Desktop Video driver before my DeckLink will be recognized.
Still running strong 30% overclock.. 

https://forums.macrumors.com/threads/mac-pro-4-1-and-5-1-pcie-aux-power.2035519/