I can not find the power button on my mother board

The green light just show that the motherboard is getting power.
The power button of the front of the case is connected to the mother board, not to the power supply, usually in the extreme lower left corner along with the with the HDD and Reset Button cords; Power button wire are labeled and usually red/black.
If all wired correctly, possible bad or stuck power button or reset button.
Hope this helps.
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Power supply or mb

sounds like a mother board issue,

start with pulling out all ram chips and re try,,

then try pulling all cards out like old modem and also cdroms.

if ever thing but power is unpluged its a bad mother board or CPU chip

look on the mother board,, with it on its side,, power button facing you.. On the Mobo look at the bottom left were all the other small plugs are. that come out of the face of the computer.. it should be marked PWB or SW

1. Check the mother board user manual 1st. To see how to properly install this mother boar to your PC cabinet or tower.
2. Check to see if you have the power from the power supply correctly connected
3. You may not have the proper watts or power from the power supply to power said mother board.
4. check the mother board battery it may not have proper voltage it should be 3.9 volts or more with a voltage meter check.
usually a 2025 button battery on the board

This can be a faulty power supply or a damaged mother board. here's how you can confirm.

When pressing the power button, inspect the cooling fan that is located on the back of the power unit where the power cord plugs in. if the fan starts then stops immediately, this will confirm a damaged power supply.

Now, if the fan continues to operate but, the CPU doesn't start to power up and load the OS, thsi will confirm a mother board issue. replace the mother board in this case.

check conections, did you isolated bolts while you ware inserting mother board? check condensators on mother board if there are some leeks... if this is the case ,,, buy a new mother board? is mother board new?

You wil have to give me more details please

Sounds like the power supply is faulting. If not it is your mother board that has failed.

Make sure that the power button is conected to the right prongs on the mother board. On the writing next to the prongs it should say power.