Desktop turns on automatically??

[808Alaska]

Hey everyone i was wondering what would cause a desktop CPU to power on automatically when you l plug the power cable in the PSU. I noticed that the Front soft power button doesnt work either. The only way to turn it off and on is to do so with the PSU power switch on the back of the PC. And also theirs no video when it turns on either. I switched the Video card but it still doesn't work. I did a hard reset (Remove CMOS battery and hold down the power button) but it still doesn't work. However i did messaround a little with the soft power switch cables that plug into the MOBO. would the soft power switch not being plugged in correctly cause this to happen?

 

[KSoD]

The cables for the power switch are not attached to the mother board properly. Check the mother board manual to find out where the cables should be attached on the mobo properly and it should fix your issue.

 

[808Alaska]

Ok. and what about the no video issue? is the motherboard shot. if i tried two different video cards and both didnt work?

 

[KSoD]

The only thing i can think of would be that the BIOS is set to use onboard not the card.

 

[808Alaska]

Oh and i forgot to mention that i also tried using the on board also and that didn't work. is it possible for just the PCI-express slot/video card controller on the mother board to have shorted somehow?

 

[KSoD]

Well that depends, did you not ground yourself properly when installing it? Did you not use the brass standoffs? Cause for sure if you didnt then yes can be the answer. But if you have then it is most unlikely.

 

[808Alaska]

it didnt work. I tried plugging in the front soft power switches in every which way possible and i even tried without then even plugged into the MOBO and it still turned on automatically.

and yes i had proper grounding and it was a prebuilt computer that worked before so i dont see what's causing this issue. how exactly does a front soft power switch work on a computer?

 

[oldskool]

it didnt work. I tried plugging in the front soft power switches in every which way possible and i even tried without then even plugged into the MOBO and it still turned on automatically.

and yes i had proper grounding and it was a prebuilt computer that worked before so i dont see what's causing this issue. how exactly does a front soft power switch work on a computer?

With ATX-type motherboards, there is a constant voltage to the motherboard from the PSU, and when the power switch is pressed, the switch sends a signal to the CPU to start the computer. There is more that goes on after that, but that is the basic CPU/switch relationship.

EDIT: I want to add that the switch does not actually "power up" the system, it merely sends a signal to the CPU to activate the system via that ever present voltage I mentioned above.

 

[808Alaska]

Ok but i even tried to leave everything plugged in except the front soft power switch and it still turned on automatically. is that indicating that its more then just a little switch problem? possibly a Motherboard problem?

 

[Kharn]

I doubt it it's not out of the realms of possibility but it could happen, walk us through what you did step by step and any changes you have made to your system you have made and we might get closer to a solution.