PC won't turn on after shut down

Hi There!

I'm new on this board :)



I have a problem with my Corsair AX850 Power Supply.



If i turn off PC and then turn it on again, PC won't start, before i unplug power supply cable and the motherboard light has gone out. If i wait until the light has gone out and then turn on the power supply, then everything is starts OK.



So, if i leave PC off for a few minutes, then it wont start unless i do turning off power supply (cable) as above.



I run this Brief PSU Functionality Test and my power supply won't start, but i connected HDD instead of fan.



What can i do? What's wrong with my PSU?



Thank you all!