When you press the OFF switch your motherboard opens those two pins, telling the PSU to power everything down safely. That is the only correct way to shut a system down - pull the jumper, then power off the PSU.
If you just flip the PSU switch off, you leave a "whole lot of amerage" suddenly looking for the quickest way to get home. And electrons aren't fussy, if they can find a shorter path across a component instead of thru it, they'll use that. If there are unseen micro droplets of solder on the solder mask that present a shorter path, they'll use that path, carbonizing the solder mask and making it an even BETTER shortcut - resulting in nasty smelling smoke and burned solder mask...
Just flipping the PSU switch to off might not break anything the first time or even 100th time you do it, but eventually you'll pay the price, and the magic smoke gets out. There's a very valid reason why you don't just turn off your computer by yanking the plug out of the wall socket - and flipping the PSU switch is the equivalent of doing that. Do that to your desktop computer a few times and see how well it runs as a result...
+1
I, for one, would like to see that shown experimentally. I personally believe there is no fault in pulling the plug.
More accurately, I believe there is no fault in pulling the plug with the miner attached to the power supply.
Still, that doesn't have a bearing on potential buildup on the power supply lines after disconnecting from the miner, plugged in with switch off or unplugged from the wall with power supply switch on. The possible problem would be the power supply outputs looking at a open given that the leads would be unplugged from the miner. The longer unplugged the higher the potential potential buildup. KnC does not know the design of every model of every power supply manufactured. If a power supply had been powered on for hours or days the potential for voltage potential buildup on the filter capacitors while leads are disconnected may very well exist in some miners.
soy