PSU automatically turns on when plugged into power cable without pressing the power button

[GOOL]

So I am in the mid process of building a new system, and I am experiencing a weird problem. When I connect the PSU into the power cable, it without doing anything or my intervention and even without my pressing the power button on the front panel of the computer. I have the proper cable plugged to the motherboard, so the power-button on the front does function. It is weird enough that it occurs, but what is strange thing is the system in fact complete POSTS, and I can access the BIOS as ell and everything. Any thoughts why the PSU automatically switches on?

[Aandaleeb]

Does the power button on the front panel also switch the computer off ? You may have the case power cable connected in a wrong manner - even if its in the correct motherboard pin-out. So therefore I think you are facing this issue , but if is still the same case then I will ask you to go directly to the vendor from whom you bought it and then get it replaced as soon as possible.

[mathews]

Typically a BIOS setting would result this odd behavior : if the computer is set to power failure setting: ON. I have my computer on this setting. It will switch on as soon as I tap the powersupply button on. And another thing if is that when I turn the system down from the Operating system it will remain shutdown. I require to push the front panel button to start it again. if the system starts at odd times without the power switch it is probably a "wake on LAN" setting which is causing the system to wake up.

[MACuser]

The front panel power button pulls one of the 20/24-pin motherboard ATX header lines to a low status temporarily. It is very doubtful to be the reason of the issue . When they rupture you just lean not to be able to turn on the system on any more , but I too think that there might be some issues with the BIOS , you have to set it there and command to start the button on power button click .