Power Supply Turns Itself ON

[JackBN]

Seasonic Platinum 660 watt modular
i7-4770K, ASRock Extreme 4, Samsung EVO SSD
APC UPS for the computer, not the printer (tried powering the printer via the UPS, no help)

Seasonic turns on the computer, with the TINIEST glitch on the wall power line.

Initially, I noticed the computer would turn on when I powered up the Printer.
Then I disconnected the printer power and USB, and the problem persisted.

After experimenting, eventually I found the computer turns on even with NO wall power load change, other than switching ON an EMPTY power strip (tried different power strips).

ANY suggestions, before replacing the Seasonic?

 

[JackBN]

As a further test, I plugged the computer into a power strip, instead of the UPS.
The computer does NOT turn on when the OTHER power strip is switched on. Thus, this solves the problem. But I want a UPS.

I tested the UPS battery briefly while it powered the computer with wall power off, and watched the remaining run time.
The run time did not drop rapidly, suggesting the battery is probably OK.
So, now my prime suspect is the APC UPS, but I don't know why.
There is NO data/UBS/digital communiation between the UPS and the computer.

Still hoping for ideas.

 

[Puffnstuff]

I would go into the bios and make sure that all of the wake on options are turned off including restart on a power loss.

 

[DigDog]

...

i would RMA the PSU. quickly.
waa wait ..
this is mind boggling; the PSU has the switch on the OFF position?!? And it turns itself on? I think you need to set a new "throw out the component" speed record with that PSU.