Question Motherboard turning on for 3 seconds then turning off

[dogester366]

Whenever I turn my psu on with the switch at the back, the motherboard and psu both turn on for about 3 seconds, then turn off and don't turn back on unless I switch off the psu and switch it back on . I looked at the motherboard manual to make sure I had the power button on the right front panel pins too. I made sure both sets of ram I tried were compatible.

Things I've tried already

• Reseating the CPU
• Using several different (known working) power supplies
• Trying it on an antistatic bag to make sure nothing was shorting
• Soldering a new cmos battery holder (Old one was half snapped off because the vertical ones are super fragile)
• Changing the cmos battery
• Resetting the CMOS both by taking out the battery and letting it sit and also using the onboard CMOS clear jumper
• Using different (Known working) RAM sticks
• Trying different RAM slots

I've tried all that I know of and it still does the same thing. Any suggestions? Its an Aaeon EMB-B75A.

 

[lvt]

Depending on the Bios setting, many motherboards will run for a couple of seconds every time you switch the PSU on. It's perfectly normal.

What happens if your PSU is ON and you press the power button on the motherboard?

 

[dogester366]

Depending on the Bios setting, many motherboards will run for a couple of seconds every time you switch the PSU on. It's perfectly normal.

What happens if your PSU is ON and you press the power button on the motherboard?

Absolutely nothing. I've tried shorting the power button pins without a power button too. Just completely ignores my input. The board is still getting power though since the power led is on. (I mean the led that signals if the board is connected to electricity, not the one that shows if its turned on.)