Question After turning it off overnight, PC turns itself on automatically with only the hdd activity LED lit up ?

[Micario]

Turned off the computer then went to sleep. When I woke up the PC is on with only the HDD activity LED lit.
I pulled the plug then tried turning it on. Without even pressing the power button it turns on by itself for a second, then powers off, only the HDD activity LED is lit again.

I opened up the computer, reseated the cmos but still the same issue.
What could be the problem here ?

 

[NanoSuit3]

Are you saying your PC turns on by itself when fully powered off or am I being fooled?

 

[Micario]

Are you saying your PC turns on by itself when fully powered off or am I being fooled?

Yes as soon as I plug it in it powers on then stops with only the HDD activity on and pressing the power button again doesn’t do anything

 

[Micario]

Are you saying your PC turns on by itself when fully powered off or am I being fooled?

With no display no bios or anything at all

 

[CountMike]

With no display no bios or anything at all

Are you sure it's actually turned off or in one of power saving states? If you are sure, have a look in BIOS for options something in stile of "What to do when power resumes. Usual options are Stay Off and Restart.

 

[Misgar]

A computer is only turned "off" when the mains on/off switch on the ATX PSU (or wall outlet) is flipped to the OFF position, or the mains lead is pulled out. For the rest of the time, the computer is in "standby" or "on". It is never "off" with mains voltage present on the PCB inside the PSU. The 5VSB rail is maintained on the mobo, meaning the mobo is always suppied with power when it's in standby mode.

Does the hard disk activity LED flash on and off, or is it continuously illuminated? Are you sure it's not the Power LED that's glowing? There have been times when I've mistakenly connected the HDD LED to the Power LED header pins on the mobo. It's easy to do.

Did you make any changes to the system or disturb any wires inside the computer case immediately before the fault became apparent?

Your motherboard could have a fault, in that it's switching from "standby" to "on" without you pressing the power button.

You could check the functioning of the power button and wiring with a multimeter set to continuity (Ohms) range. If the two wires are touching intermittently, this would explain the spurious switch on fault.

If the switch and wires check out OK, the fault probably lies in the motherboard. There's even a vague chance the PSU is at fault. If you have a suitable spare mobo and psu, swap them into the case and see if the fault persists. If it does, the case wiring is at fault.

If you want to stop the PC switching on by itself, switch it off at the wall or by the switch on the back of the ATX PSU. Don't leave it in "standby" mode.

 

[Jason-Julius]

Turned off the computer then went to sleep. When I woke up the PC is on with only the HDD activity LED lit.
I pulled the plug then tried turning it on. Without even pressing the power button it turns on by itself for a second, then powers off, only the HDD activity LED is lit again.

I opened up the computer, reseated the cmos but still the same issue.
What could be the problem here ?

Probably it was seen that it was a hardware issue possibly related to the motherboard or power supply. I will recommend you get checked your PC by a technician to diagnose the problem and resolve it accurately.
Thank you.

 

[Micario]

Yea I concluded that it's a hardware issue concerning the motherboard or the PSU so i'll just replace it as a whole thank you for the inputs

 

[Jason-Julius]

Yea I concluded that it's a hardware issue concerning the motherboard or the PSU so i'll just replace it as a whole thank you for the inputs

No need for this man.