yaapelsinko Posted September 8, 2019 Report Share Posted September 8, 2019 After I turn my PC off and the PSU is in stand-by mode, it starts to whine like a mosquito. It doesn't whine though if I cut AC power off and then plug it back in. In this case I can see some motherboard leds are lit (they usually are lit in stand-by mode), so the PC is in stand-by mode again, but PSU is not whining. Also, there's no whining when PSU is on. Whining start only if PC/PSU was turned on and then turned off. What do I do with it? Because usually such coil whining is an indicator of high load, and it should not be. It looks like the PSU is shutting down incorrectly. Quote Link to comment Share on other sites More sharing options...
yaapelsinko Posted September 10, 2019 Author Report Share Posted September 10, 2019 Meanwhile I have new observations. It is endeed caused by overload in stand-by mode, because I've found the motherboard doesn't shutdowm chassis fans when PC is turned off. 2 of 3 of the chassis fans are working on the idle RPM. Also I've noticed flashes from under the PSU, like if its own fan's leds were working. The motherboard is ASUS H97-Pro, and there was no such issue with the two priveous PSUs (one Deep Cool and one an older Toughpower model). The thing is, the problematic shutdown happens only if called from the OS. If I reboot the PC and then shut it down before the OS is loaded, then it turns off correctly and all the fans are stopped. Quote Link to comment Share on other sites More sharing options...
yaapelsinko Posted September 10, 2019 Author Report Share Posted September 10, 2019 Aight, I'm smart so I kinda fixed the issue, but with that fix comes another issue. The power draw was caused by the USB connection between PSU and MB. I shut down the PC, okay, the whine is there again. I pulled the PSU-MB cable out aaaand the whine is gone. Now, for what I know, USB is 5V. The power draw, however, was caused by the fans connected throught the MB, isn't it 12V circuit? Two of them (PWM ones) had theid leds still on, the third (DC one) was off, but the whine changed its tone when I was turning the fan manually, so there is clearly an electrical connection between them. All of it ended once I've unplugged the PSU-MB USB cable. Well, that would be alright, but how am I supposed to control the PSU now with the cable unplugged? Clearly there is some kind of an incorrect electrical loop caused by the PSU's USB-connection, how to fix it? Quote Link to comment Share on other sites More sharing options...
yaapelsinko Posted September 10, 2019 Author Report Share Posted September 10, 2019 The answer was enabling "ERP" or, in my case, "Deep S4 state" in BIOS. Or S5 in newer motherboards. No thanks to the support. Still, it's a workaround, it shouldn't happen in other states, or should it? Quote Link to comment Share on other sites More sharing options...
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